Pregnancy Part 1 | Triage Thoughts Ep. 220

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Why pregnancy is worth understanding

Pregnancy is, in many ways, the root of all the differences between the sexes. Women get pregnant, and a great deal of the anatomical, physiological and hormonal differences between men and women exist to make that possible. Even the topics we have already covered in this series, such as the menstrual cycle, are really about pregnancy. When we describe the follicular phase, the luteal phase and menstruation, we are describing what happens when a woman does not become pregnant. Pregnancy is the unique physiological state that all of that is geared towards.

It is also a very relevant topic for the people who listen to us. A large share of our audience are women in the 25 to 35 age range, which in Ireland is the time when most women are thinking about trying to conceive. It is a subject that personal trainers and nutritionists often find difficult, because it is hard to know where the line sits between general information and advice that should only come from a doctor. The same caution applies to us here. We are sharing information drawn from bodies such as the American College of Obstetricians and Gynecologists and from general guidelines, but as coaches we can only go so far.

The good news is that in most developed countries, and certainly in Ireland, the care during pregnancy is generally very good. You will have checkups with your GP, a 12 week checkup, advice on the appropriate vaccines, and dietary guidance. The systems are there to support you. What many women still want, though, is to feel empowered going into it, to understand what lies ahead rather than knowing nothing beyond the nausea and vomiting they may have seen others go through. So this is genuinely worth learning about.

A note before we go further: this is part one, and it covers nutrition. We have left training for a later episode, because the training side carries more nuance and more interpretation on our part.

The basic anatomy of pregnancy

The uterus is the major organ to think about. It sits in the pelvis, in your lower abdominal area. Inside it, the placenta forms and the fetus grows, and over the course of pregnancy that space expands and affects everything around it.

It is worth thinking about this purely anatomically first, before any hormones come into it. As the uterus grows it takes up more and more room in the abdominal cavity, so the other organs have to shift or get compressed to some degree. It pushes up against the diaphragm, so every breath has to work against that upward force, especially towards the end of pregnancy. It can press on blood vessels and change how blood flows. A great many of the symptoms of pregnancy come from nothing more than this large, space-occupying uterus and fetus.

One detail matters here: the bump grows forwards. The uterus and fetus do not bulge out to the sides and the back in equal measure, they push out the front, which is why you see the familiar shape of pregnancy. That anterior growth has knock-on effects we will come back to.

Inside the uterus, the lining, the endometrium, is normally shed during menstruation. During pregnancy that does not happen. Instead, largely through the role of progesterone, that lining is nourished, and it becomes the place where the placenta implants. The placenta is an organ unique to pregnancy. It acts as the barrier between mother and baby, managing the transfer of a great many biological molecules. If we keep it simple and just think about blood and nutrients, the placenta sits between the two circulations, and the umbilical vessels carry that exchange between the fetus and the placenta in both directions.

The baby is suspended in amniotic fluid. For most of fetal development the lungs are effectively filled with fluid, so the baby is not breathing in the usual sense. Gas exchange happens through the placenta and umbilical vessels instead. This becomes relevant later, because a reasonable question is whether heavy lifting and the pressure that comes with it might cut off blood flow to the baby. We will return to that, but the basic picture to hold is of those vessels doing the vital work of transfer.

What changes in the cardiovascular system

Several changes happen to support all of this. Plasma volume increases, which means there is more fluid being pumped around the body. One consequence is anaemia. This is largely a dilution effect: red blood cell volume does rise, but plasma volume rises by more, so you end up with relatively lower haemoglobin. That has two practical implications, one for nutrition, such as making sure you get enough iron, and one for exercise, because less haemoglobin can reduce your exercise capacity.

Cardiac output also goes up. A pregnant woman will generally have a higher heart rate and a greater stroke volume, so more blood is pumped with each beat. Pregnancy is genuinely a stressor on the cardiovascular system, and that has implications for aerobic exercise that we will deal with later.

This is also a good moment to start thinking ahead. If pregnancy is a cardiovascular stressor, then it makes sense to ask what you can do to prepare for it. Exercise generally improves your tolerance of cardiovascular stress, and there are nutrition and lifestyle levers you can pull too. The point is not only to react to what happens during pregnancy, but to set yourself up well before it. Being in better health and fitness in advance, with better nutrition, is one of the things you see time and again that improves the chance of good outcomes.

How hormones shift during pregnancy

The hormonal picture differs from the menstrual cycle. Early on, the corpus luteum acts as a buffer, releasing oestrogen and progesterone until the placenta is mature enough to take over. After that handover, oestrogen and progesterone rise gradually throughout the rest of pregnancy.

That gradual rise matters. Progesterone acts as a smooth muscle relaxant, so it helps the blood vessels dilate, which reduces vascular resistance. This is important because of everything we have just described. With more fluid, more plasma volume and higher cardiac output, you would normally expect a large rise in blood pressure. The dilation of the blood vessels offsets that, allowing blood pressure to stay normal or even sit slightly lower than usual.

This is why blood pressure monitoring becomes so important in pregnancy. Any rise in blood pressure sets off alarm bells as potentially abnormal, and it is something your obstetrician will watch closely. This is also why preparing well beforehand matters: complications such as preeclampsia, where blood pressure rises during pregnancy, and gestational diabetes, where blood sugar rises, are among the things that good pre-pregnancy health can help guard against.

The downstream effects of a growing uterus

As you move into the second and third trimesters, the simple fact of the uterus, fetus and fluid taking up space produces effects across several systems.

In the respiratory system, the pressure up against the diaphragm means it has to work harder, and you tend to have some relative hyperventilation, breathing a little faster. This can be difficult lying flat. If you were lying on a bench trying to breathe with all that pressure pushing up against the diaphragm, it would be hard work.

In the genitourinary system, the bladder is compressed. A bladder might hold around 600 millilitres, and that chamber is now being squeezed by a much larger one. This is why incontinence can become an issue, and why a pregnant woman often needs to get to the bathroom quickly. In the gym, trying to stay well hydrated while lifting heavy adds pressure on the bladder, which can mean more trips to the bathroom.

In the digestive system, all of that pressure within the abdominal cavity affects digestion. A large meal, or a build-up of gas, can mean more reflux and more flatulence. There can also be compression of the veins or lymphatics returning fluid from the legs, which can lead to more swelling on one side than the other. That said, some swelling is a normal part of pregnancy anyway, because of the increase in plasma volume.

The increased clotting risk and why movement matters

Pregnancy is a hypercoagulable state, which means there is an increase in clotting factors and a greater risk of a clot forming. A deep vein thrombosis, a clot in the deep veins of the legs, is one example, and the danger is that it can travel up through the venous system to the lungs and cause a pulmonary embolism. We mentioned in the last episode that the pill carries an increased risk of clots, and the risk during pregnancy is greater still.

This is one of the strongest reasons to keep moving. Being sedentary is a major risk factor for clots, because one of the things that contributes to them is stasis, blood that is simply not moving. When you walk around and stay active, your muscles contract and pump blood back from the extremities, which lowers that risk. Maintaining physical activity through pregnancy is genuinely protective.

A word of perspective

Two things are worth saying before we move on. The first is that humans are built to exercise, so you should keep up movement and exercise through pregnancy, while listening to your doctor’s specific advice. The second is that humans are built to go through pregnancy. Reading a list of things that can go wrong can be alarming, but there are billions of us, so it clearly does not go wrong all that often. Pregnancy should not be seen as a catastrophe that requires you to overhaul everything. Your body is designed for this. The goal is simply to be in the best health to go through it, and to go through it in the healthiest way.

Getting your nutrition right before pregnancy

Nutrition before pregnancy matters as much as nutrition during it. Pre-existing conditions such as obesity, diabetes or high blood pressure are risk factors before you even conceive. A very high BMI, for instance, increases the risk of complications for both mother and baby. So if you are thinking that you would like to have children in the next few years, improving your fitness, your diet and your body composition beforehand is likely to improve outcomes.

This can be a difficult message to deliver, because women can torture themselves after a complication, asking what they did wrong and whether it was their fault. It is important to keep risk in perspective. Most of what goes wrong in human health is chaos and randomness, and what we are trying to do is get some control over it. When we talk about risk factors, we are usually talking about relatively small effects, not certainties. So if there is a complication, do not beat yourself up, but do recognise that there are things within your control.

Body composition matters in both directions. Excess body fat is one concern, but chronic undernutrition and chronic over-exercising are very common in athletic populations and can reduce fertility. We have discussed this before in the context of amenorrhoea, the absence of periods, and the point is not only the missing period but the potential effect on future fertility. Women naturally carry a higher body fat percentage on average, and part of what that supports is a healthy, fertile environment for reproduction. Chasing visible abs and very low body fat as a woman is not likely to help fertility. The aim is balance, a healthy level of body fat, neither too lean nor carrying excess.

It is also about the overall nutrient density of your diet. Eggs begin to mature roughly 90 days before they are released, so that is the window in which you want your nutrition to be in a good place. Ideally you want to be eating a nutrient dense diet, not smoking, not drinking alcohol and not taking recreational drugs in that lead-up. To be clear, this is not the same level of risk as drinking or smoking during pregnancy, which is what you most want to avoid, but doing the right things beforehand all works in your favour.

In practice, although the egg maturation window is around 90 days, it is wiser to think in terms of the six months before you want to conceive. Changes take time. If you have high blood glucose, switching your diet 90 days out will not fix it overnight. Some changes are measurable and physiological, others are slower shifts in how your genes are expressed, and both need a run-in. Treat the six months beforehand as the time to look properly at your diet, sleep, stress and lifestyle, so you go in with the best fertility and the best eggs.

Why blood glucose matters so much more during pregnancy

Here is a useful way to understand the urgency. If you or I had somewhat dysregulated blood sugar, perhaps after a long bulk, we might decide to finish the bulk and then sort it out over the following six months or even a year. Moderate increases in blood glucose are a risk, but for a non-pregnant adult the damage plays out over decades, so we accept that and take our time.

Pregnancy is different. The same rise in blood glucose now plays out over the roughly nine months a fetus is developing, and the fetus is extremely sensitive to its environment. A high glucose supply can cause complications. A baby born after a high glucose supply during pregnancy can become hypoglycaemic shortly after birth, because its own physiology is immature and it suddenly loses that high supply and cannot regulate well. There are longer term metabolic risks too, such as a higher risk of diabetes and obesity. The point is that something we might tolerate over years in a non-pregnant person can become genuinely important when compressed into a few months of fetal development.

You generally will not have to measure all of this yourself. If gestational diabetes develops, it is usually managed medically, often with metformin, alongside dietary changes, so there is no need to panic about monitoring everything. You will be looked after. The lesson is simply to respect how condensed and sensitive that window is.

Prenatal supplements and the food-first approach

Before pregnancy, prenatal multivitamins are worth considering. Many women take an all-in-one prenatal product, and you generally do not need to hunt down folic acid, iron and everything else separately. Folic acid is the big one, and omega-3s, particularly DHA for brain development, are important both before and during pregnancy.

Our general preference is always food first. If you can get what you need from food, all the better, and we have talked before about what a good diet looks like. But that is not always possible, and you may not have the time or the skills to calculate, say, your folic acid requirement and then your folic acid intake from food. If you have a generally good diet but want to be sure you are covering everything for a healthy pregnancy, a prenatal multivitamin is sensible.

Choose a reputable, certified brand rather than a random corner-shop product. And do not assume more is better. Going overboard can cause toxicity, and during pregnancy excess of certain nutrients can be teratogenic, meaning harmful to the developing child. For most ordinary nutrients this is not a concern unless you are megadosing one or two of them, so this is not meant to scaremonger. It is simply a reason to be careful with amounts.

The myth of eating for two

One of the most common ideas around pregnancy nutrition is that you are now eating for two. People say it constantly, often to women who are being careful with their diet, encouraging them to eat more.

It is easy to see why this idea took hold. In a tribe with limited food, prioritising a pregnant woman makes evolutionary sense, so the instinct is deeply conserved. But it is not actually true, and there are risks in both directions, eating too much as well as too little. Without controlled research, no one could really know how much weight someone should gain, so the old advice is understandable, it is just not accurate.

We do not expect pregnant women to track calories, but a rough idea of the surplus is useful. In the first trimester you often do not even have a bump yet, body weight does not change much, and you generally do not need many extra calories at all, so roughly maintenance is fine unless you were previously in a deficit. In the second trimester you usually need somewhere between 200 and 350 extra calories a day. Take 300 as an example, and across a week that is around 2,100 extra calories. In the third trimester it is somewhere between 300 and 450 extra calories a day, and in the final weeks you may not need even those.

These are generic figures, and other things modify them. Some women stop work or greatly reduce their activity, which changes the picture. But the headline is that this is nowhere near eating for two. If your maintenance was around 2,200 calories and you add 350, that is a 15 to 20 percent increase, not a doubling. Some people genuinely do take it that far, which is the thing to avoid.

How much weight to gain, and why your starting point matters

Calorie intake ties directly to weight gain, and the right amount of weight gain depends heavily on where you start.

If you were a normal weight before pregnancy, within a healthy BMI range, you are generally looking at somewhere between 10 and 15 kilos of weight gain, which is roughly 25 to 35 pounds. If you were underweight, you should probably gain more than that. If, for example, you had just come out of a bikini competition and were very lean when you conceived, you would want to gain more, much as people who get very lean for a contest understand they need to regain some weight to get back to good health. The same logic applies here: some of that gain is simply getting you back to a normal, healthy level of body fat, and then there is the pregnancy weight on top.

If you were overweight or obese going into pregnancy, there is less need to keep gaining, because you already have additional energy stores, and pushing weight gain further carries its own metabolic risks. As a rough guide, a BMI over 30 generally means aiming for no more than around nine kilos of weight gain. These figures vary with individual circumstances, though. A very muscular person, a very frail person, or someone with an unusual nutritional history in the lead-up to pregnancy may be given different recommendations, so this is something to discuss with your doctor.

It is worth remembering where the weight comes from. Yes, there is fat accumulation, and you want some extra fuel available, but a good deal of the weight is the developing child. People sometimes forget that. They step on the scales, see the number up, and panic, when the fetus simply has to weigh something. This matters because clients in health and fitness populations can be very anxious about weight on the scale, insisting they should sit at a particular weight. During pregnancy you have to account for another human growing inside you.

This is not a cosmetic point. Weight gain has a bearing on insulin sensitivity, blood lipids and other cardiometabolic markers. As we said, for a non-pregnant person a lot of this is cumulative and can be addressed over time, so there is less urgency. In pregnancy it is time-constrained twice over: it plays out over nine months, and it is affecting a child whose development will carry effects through their whole life. That is true for both undernutrition and overnutrition, which is why getting it right matters.

Insulin resistance and gestational diabetes

Insulin sensitivity decreases during pregnancy, so you become more insulin resistant and blood glucose tends to rise. To some degree this is normal, but it can become excessive. In a healthy pregnancy, the mother still produces enough insulin to drive glucose out of the blood and into muscle and fat cells, keeping it in a safe range. She compensates for the insulin resistance by producing more insulin.

In gestational diabetes, that compensation fails, and you end up diabetic during pregnancy, insulin resistant with high blood glucose. This is usually managed medically, often with metformin, alongside dietary changes, again because the window is so sensitive. It is another reason not to go overboard trying to eat for two, especially if your body fat was already high or your metabolic health was already poor.

The challenges that make eating well hard

Beyond the principles, several real challenges get in the way of eating well during pregnancy.

The first, in the early stages, is nausea and vomiting. A certain amount is normal in the first trimester and typically eases by the second. It can become severe, a condition called hyperemesis gravidarum, which usually means admission to hospital and proper management, because heavy vomiting can cause electrolyte disturbances and serious dehydration. Even in milder cases, food aversions and general digestive upset make it hard to eat your normal balanced diet. Looking at the chicken, wrap and rice you used to eat may hold no appeal, and you may gravitate towards whatever is easy to digest, tasty or simply what you are craving.

Food aversions are an interesting challenge in their own right. Women tend to have more food aversions than men, and this is thought to be evolutionarily conserved because it may keep both mother and fetus safer. A common one is an aversion to protein. A food someone happily ate before, such as eggs, can suddenly become repellent, the texture alone enough to put them off. The thinking is that some of these foods can introduce pathogens to the mother and therefore the fetus, with the risk of miscarriage, so an aversion protects against that. There is also a hypothesis specifically around protein: ammonia is a byproduct of protein and nitrogen metabolism, and ammonia is not good for cells in general, and particularly not for a developing fetus, which cannot handle it the way a fully developed adult can. So there is an evolutionary logic to a mild protein aversion.

The difficulty is that you still need protein, both for yourself and for the child. Protein is far more than a building block. Yes, you are building a child and need the raw materials, but protein is also a signalling molecule, the trigger for muscle building and with other signalling effects in the body. Getting enough protein while dealing with nausea, vomiting and aversions is one of the hardest things for pregnant women to manage. If you are pregnant or thinking about it, expect this, and expect that your perfect plan for your diet may need to flex.

Into the second trimester, cravings and appetite take over. Women often crave foods they have never eaten or would not normally touch, sometimes in odd combinations. In some cases this can manifest as pica, a craving for non-food items. People have been known to crave dirt or sand. This is sometimes linked to mineral or nutrient deficiencies. The obvious advice is not to eat dirt, because it will not help you or the baby, but it is worth raising with your doctor, who may investigate whether there is, for example, a magnesium deficiency behind it. Doctors have heard it all before and can help or refer you on. The simple takeaway is: do not eat dirt.

By the third trimester, energy needs are higher, you are dealing with weight gain, and the pressure of the fetus and fluid pressing into the abdominal cavity affects digestion. This is where reflux and heartburn become more likely. Reflux tends to be worse with larger meals, yet you need to meet higher energy needs, so spacing meals out helps. Rather than three very large meals, six smaller ones may suit better. The aim is to find the point where you meet your energy needs without eating so much at once that you trigger a lot of reflux. This matters especially at night, because lying flat already increases reflux, so a very large meal before bed can be a problem.

Foods to avoid during pregnancy

There are foods you are advised to avoid, largely because of the risk of pathogens and because the developing fetus is so sensitive. Recommendations tend to be cautious here. Even if the chance of a problem from a given food were one in a thousand or one in ten thousand, most women will choose to avoid it, simply because of how sensitive the environment is.

Honey is one to flag, though it applies more to babies than to pregnancy itself. You are not supposed to give honey to infants, and people do it all the time out of ignorance, but it can be deadly to a baby. This connects to a broader point. A newborn is not fully developed. Ideally humans would gestate for something closer to 12 to 16 months, but a baby that size could not be born safely, so there is an evolutionary trade-off between developing the child as much as possible in the womb and still being able to deliver it. Caesarean section helps to some extent but is not ideal either. The upshot is that some of these cautions extend beyond pregnancy into breastfeeding and into the introduction of solid foods.

The foods to be careful with include unpasteurised milk products, mouldy cheeses, raw and undercooked meat and eggs, smoked fish, high-mercury fish such as tuna, swordfish, marlin and shark, raw shellfish, and excessive liver. With the recent trend towards eating large amounts of raw meat, there is a real question of whether we will see more pathogen-related problems. We started cooking food for good reason, and there is no need to go back to eating everything raw. Some foods can be eaten raw safely in a non-pregnant state, sushi being the classic example, but during pregnancy it pays to be more careful.

Two separate reasons sit behind this list. Some foods are risky because of pathogens, which is the concern with raw or undercooked items and with smoked fish, which is not fully cooked. If smoked fish is your main way of getting fish in, and we do recommend eating fish in pregnancy, the ideal is to choose another cooking method, or to cook it further, which rather defeats the point of smoked salmon, but that is the trade-off. Other foods are risky because they sit higher up the food chain and have bioaccumulated heavy metals. This is the issue with large fish such as tuna. You can have some tuna, but ideally you would limit it because of that heavy metal accumulation, which is not good for a developing fetus.

Excessive liver deserves its own mention. Liver is extremely rich in vitamin A, and excess vitamin A is potentially teratogenic, particularly in roughly the first 60 days of pregnancy. So loading up on raw or even cooked liver throughout pregnancy would be a bad idea.

This is not an exhaustive list, and it is shaped by culture. Our examples reflect a fairly standard Irish diet, and other cultures eat foods we simply have not thought to mention that could fall into the same risky categories. So it is worth looking at your own diet, talking to your medical providers, and checking the relevant government or health-organisation guidance to understand not just what is on the list but why, so you can spot anything you eat regularly that belongs in the same category even if it is not named. These recommendations also get updated over time as the evidence develops.

Caffeine, alcohol, smoking and sugar

Caffeine and alcohol are the more familiar ones. With caffeine there is some uncertainty about the exact threshold. The American College of Obstetricians and Gynecologists recommends limiting it to 200 milligrams a day, so in theory you could have a coffee and a little chocolate. In practice many women cut it out entirely, reasoning that they do not love coffee enough to tolerate any extra risk, and that sensitivity varies between people anyway. High caffeine intake is associated with increased risk of miscarriage, potentially reduced birth weight and stillbirth, so many simply decide it is not worth it.

One thing people underestimate is the caffeine in chocolate. Some major brands are surprisingly high, and a whole bar can approach 200 milligrams. For a pregnant woman with a chocolate craving that is something to be aware of, but it is worth knowing generally too. A few squares before bed is usually no issue, but if you are caffeine sensitive, have already had a lot of caffeine that day, or have picked up a speciality bar with far more caffeine than usual, it can affect your sleep. In pregnancy, the point is that caffeine adds nothing. It does not improve the health of the mother or the fetus, so cutting it down or out is a reasonable choice.

Alcohol is a flat no. Almost everyone recommends zero tolerance, on the basis that no amount is known to be safe. That does not mean a drink before you knew you were pregnant, at six or eight weeks, represents a huge increase in risk, but the ideal is zero. Alcohol in pregnancy is linked to many complications, birth defects and fetal alcohol syndrome. Smoking is the same: not strictly a dietary factor, but zero tolerance, with an increased risk of many complications during pregnancy and longer term effects on the child, including respiratory and cardiovascular disease.

Excess sugar belongs in this section too. In a healthy non-pregnant person, a packet of jellies with 50 grams of simple carbohydrate now and then is no big deal. In pregnancy you have to remember that your blood is feeding the child, and the child may not be able to handle a large bolus of sugar at its stage of development. We want a more stable blood sugar level for the fetus, and we want to avoid biasing towards gestational diabetes or preeclampsia, both of which a high-sugar diet can push towards. There is also a suggestion that a high-sugar diet during pregnancy can influence the child’s taste preferences, both in the womb and into childhood and adulthood, so the child may end up with a strong preference for sweet foods. That makes weaning harder when you are trying to introduce things like vegetable purees, and it makes the child’s life harder too.

The practical message on sugar is to keep it modest but not to obsess if it comes from healthy choices. We are not telling you to avoid fruit. If you crave something sweeter, fruit is fine, because you still get some sweetness without handing the baby a huge bolus of sugar. We do want to minimise highly processed foods, but fruit is firmly approved. Keep the added sugar down, do not worry about healthy choices, and eat your fruit.

The nutrients to prioritise

Alongside the things to avoid, there are nutrients to make sure you include.

Protein is very important for the child’s growth, just as it is for our own muscle mass and bone strength. There may be barriers to getting enough, such as food and protein aversions, but the aim is to maintain protein in your diet and get some at each meal, as we usually recommend. Protein is, in fact, the main determinant of growing big and strong, far more than the old line about eating your vegetables. You can see it across the development of civilisations: populations with higher protein intakes tended to be taller, and as societies began eating more protein they grew taller and bigger. The one society we are aware of where this has not held is India, where the disease and pathogen burden is thought to prevent the benefit from showing, so it is more of a medical issue to resolve first. Broadly, though, if you want robust children, prioritise protein.

Omega-3s are next. DHA in particular supports fetal brain development, and most people would prefer their child to be bright. You can get omega-3s primarily through fish in the diet, or by supplementing. If you are vegan or vegetarian, this becomes more complicated and you need to be more careful, but an algae-based omega-3 supplement serves well.

Vitamin A is important during pregnancy, but as covered above, excess can be teratogenic, especially in the first 60 days, so be cautious with very rich sources such as liver and with double-dosing supplements. Vitamin D is also important and can come from sunlight or the diet, and it can be supplemented.

Folic acid is one of the big ones. The guidance is around 400 micrograms a day before pregnancy and around 600 micrograms a day during pregnancy and while breastfeeding, from food or supplements. Most women are advised to take a folic acid supplement, commonly in 400 microgram doses, though there are varying recommendations for different medical conditions, so this is something your doctor will usually recommend actively. Folic acid is one of the most important nutrients for preventing neural tube defects. Early in pregnancy the central nervous system develops, including the spinal cord and brain and the closing of the spaces around them, and a lack of folic acid can lead to defects there. Many foods these days are fortified with folic acid, particularly grains and cereals, which is helpful both before and during pregnancy, and folate is used in many processes in your own body too. As with everything, do not megadose. You do not need excessive intake to get the benefit, so sticking to roughly 400 to 600 micrograms is the way to go.

Calcium is needed at around one gram a day, which is achievable on a mixed diet, especially with dairy. Vegans and vegetarians need to be more deliberate about it. Iodine is also important, and it is one of the nutrients of concern in the Western world, with many people not getting enough. We covered iodine and where to get it in a previous episode on nutrients of concern for women, so we will not repeat all of that, but make sure you are getting it in. We are not aware of a specific iodine intake figure for pregnancy. Iron matters too, with a recommendation in the region of 30 to 60 milligrams of elemental iron, which is achievable on a mixed diet, particularly if your protein comes from animal sources, with vegans and vegetarians again needing more care.

Salt is the one to keep on the lower side, especially if yours tends to be high, because it matters for blood pressure management. This is largely baked into the rest of the advice: if you are not eating a lot of ultra-processed food and not eating out constantly, where most dietary salt comes from, your salt intake is probably already in a good place, unless you add a lot at the table.

Keeping it simple

The way to handle all of this without it becoming overwhelming is to keep it simple. Build a rough set of daily menus from nutrient dense foods. It is not about eating perfectly. If you have a handful of breakfast, lunch and dinner options that you know cover your protein and your omega-3s, you are not tied to a strict meal plan or to calorie tracking, which you ideally want to avoid. Pregnancy is a hard enough time without adding nutrition stressors. A rough plan with options is the wise approach.

Nutrition while breastfeeding

Breastfeeding raises a common question: do you keep eating more, or focus on losing the weight gained during pregnancy? Many women want their pre-pregnancy body back and consider eating in a deficit while breastfeeding.

Breastfeeding increases overall energy output, so it still requires additional calories to some degree. We are not certain of the precise recommendations, partly because so much has changed at once, with the fetus and uterus no longer there to carry around, but breastfeeding itself is an energy-intensive, ongoing process. As far as we are aware, the sensible target is around maintenance or slightly above. We would not focus on fat loss. Some weight loss may happen naturally, which is fine, but the aim is a well-balanced, healthy diet roughly at maintenance rather than deliberately cutting.

How long you breastfeed affects this. In hunter-gatherer societies women often breastfed for around two years, which in modern Western society can feel excessive and tends to attract odd looks once a child is a toddler. In most Western societies the six-month mark is roughly where many stop. Up to that point, treat it as an energetic endeavour: you still need to fuel both the production of breast milk and the demands of looking after a baby, including the sleepless nights. We would not overemphasise fat loss here. Crash dieting, losing something like a kilo a week, is not sustainable and is probably not good for milk supply.

Breast is best. Breastfeeding rates in Ireland are unfortunately low compared with some other countries, somewhere in the region of 30 to 40 percent, which is lower than you would want. If you can breastfeed, it is better for outcomes. There are genuine reasons some women cannot, whether other obligations, medical reasons, problems such as mastitis or a poor latch. Specialist nurses can help with latching and getting breastfeeding established. But where it is possible, it is the better option.

The reason comes down to how complex breast milk is. It is not just a matter of matching macronutrients and a few micronutrients. Breast milk, and colostrum in particular, which is the first expression, is remarkably complex. It contains hormones such as melatonin, and the composition shifts through the day. Milk expressed in the morning may carry slightly more cortisol, which could make a baby more wakeful, so giving morning milk at night might keep the baby awake rather than helping them sleep. We have not fully mapped all the constituents of breast milk or their effects across the day and across the months.

Crucially, breast milk also carries maternal antibodies and immune signals that are important for the baby’s immunity and immunological priming. This connects back to honey: an infant’s gut lining has wider gap junctions, which exist precisely to let immunoglobulins and components of the mother’s immune system pass into the child. The downside is that other things can pass through too if you are not careful, which is part of why honey is dangerous for infants. In effect, breastfeeding gives your child your immune system. Trying to reproduce the immune component in a powder is extremely difficult.

We expect that medical and scientific advances will eventually produce something very close to an optimal human feed, and the dairy industry is improving its formulas. There may come a point where breast is best no longer holds. But as things stand, the scientific literature supports breast as best. This is also a useful reminder that we often think we understand far more than we do. Anyone who studies biology or nutrition comes to realise how much is still being discovered in foods, and with something as intricate as the immune factors in breast milk, the gap between what we can measure and what nature already does is wide.

Recovering between pregnancies

A final point concerns what happens after pregnancy and before any future one. There is what is called the depleted nutrient hypothesis, the idea that the first child draws down the mother’s nutrient stores, so that without deliberate replenishment a second or third child has less to draw on. Many of the nutrients in question are fat soluble, which move more slowly than water-soluble ones.

Consider the maths. If you have a first child at 25, you spent 25 years building up the stores that first pregnancy used. If you have a second at 27, you have had only two years to replenish what took 25 years to build. So it is worth focusing on a really nutrient dense diet after pregnancy, both for the mother’s own health and for any subsequent pregnancies.

This is where family planning helps. Giving yourself time between pregnancies to recover and replenish your nutrient status is an advantage. As with the breast milk question, there are likely many things transferred to the baby that we are not yet certain about, so the best thing you can do is maintain a nutrient dense diet and, if you are planning another child, treat the gap a little like an off-season, getting yourself ready to go again. Many people leave around two years between children for exactly this reason, because recovering and getting prepared again is harder over a shorter gap. There is guidance on the optimal interval between pregnancies, with differences in outcomes when the gap is very large or very small, but the detail of that is beyond what we are covering here.

We have not touched on training in this episode. That carries more nuance and more interpretation on our part, with some hard guidelines but a lot that comes down to judgment, so we will cover it separately.