PRENATAL AND POSTNATAL NUTRITION

Nutrition plays an important role during pregnancy time and nutritional needs adapt to different stages of the pregnancy journey. This article will highlight the main nutritional considerations before, during and after pregnancy.

Preconception Nutrition 

Consuming a balanced and varied diet becomes even more important when trying to get pregnant. 

There is emerging evidence about the benefits of the Mediterranean diet in terms of fertility for both men and women (1, 2, 3).  

The Mediterranean diet involves consuming:

• A high intake of fruit, vegetables, whole grains, legumes, herbs and spices
• Olive oil and nuts on a daily basis
• 1-2 portions of oily fish per week (e.g. salmon, sardines, anchovies, trout, herring, pilchards, sprats and mackerel)
• A moderate intake of eggs, dairy and poultry
• A low intake of red and processed meat, and foods that are higher in saturated fat, sugar and salt
• Water as the main drink, and moderate amounts of red wine (for those who choose to drink alcohol)

Part of the beneficial effect of the Mediterranean diet on fertility may be related to its antioxidant and anti-inflammatory effect. Antioxidants reduce oxidative damage from free radicals in our environment, which includes protecting sperm and egg health (4, 5). Examples of antioxidants include; vitamin C, vitamin E, selenium and carotenoids, and these are found in higher amounts in fruits, vegetables, nuts, seeds, spices and herbs (6). There is some low quality evidence that antioxidant supplements may be helpful for fertility (7, 8). However, the evidence is inconclusive overall. Therefore, unless advised otherwise by a registered healthcare professional, it is often best to focus on consuming antioxidants from a varied diet rather than supplementation. A varied Mediterranean diet should also provide other important nutrients for fertility such as iodine, iron, omega-3, zinc, choline, vitamin B12 and other B-vitamins.  

It is very important for women who are trying to conceive to take a folic acid supplement for at least 3 months prior to conception up until the 12th week of pregnancy (9). Folic acid is the synthetic form of folate (or vitamin B9). This vitamin plays an important role in DNA formation, red blood cell and nerve function (9, 10). During pregnancy, a deficiency of folic acid can increase the risk of a baby developing a spinal issue called a neural tube defect, such as spina bifida . The NHS recommends a dose of 400 micrograms of folic acid per day, although some women may be advised by their GP to take upto 5mg of folic acid per day depending on their medical history (9). Some women may need to take a methylated or active form of folate supplement if they have a specific mutation on the MTHFR gene which impacts folate absorption (11). Folate should also be consumed in the diet, this can be found in broccoli, brussel sprouts, green leafy vegetables, legumes and in fortified products (9, 10).

Along with folic acid, pregnant women in the UK are also advised to take a 10 microgram vitamin D supplement. So for those who don’t already take a daily vitamin D supplement, it is often a good idea to start taking this supplement when trying to conceive (12). 

Alcohol consumption is another important prenatal consideration. The UK Chief Medical Officer recommends that the safest approach is to completely avoid alcohol for women who are trying to conceive (13). Drinking alcohol during pregnancy increases the risk of developmental problems for the baby, foetal alcohol syndrome, premature birth, low birth weight and miscarriage (13, 14). A high intake of alcohol may also be harmful for sperm health (15).  

A high intake of caffeine may impact fertility and increase the risk of a low birth weight baby, so it is sensible for women who are trying to conceive to limit their intake of caffeine to 200mg per day, which is the recommended amount during pregnancy (16). 200mg of caffeine is approximately 2 cups of instant coffee or 3 cups of tea (17). Caffeine is also found in chocolate, cola, and energy drinks.

Although nutrition is one important piece of the puzzle when it comes to fertility, many other factors impact fertility such as: genetics, medical conditions, smoking, stress, physical activity and other lifestyle factors. Roughly one in seven couples struggle to conceive, so if this is the case you can seek support from your GP and, depending on the situation, a fertility specialist. See here for more information about fertility issues from the NHS.

Nutrition During Pregnancy 

Dietary guidelines during pregnancy do not differ significantly from the guidance for the general population, such as The Eatwell Guide or the Mediteranean diet (described above). However, there are some key changes that are important to be aware of. For example, pregnant women should not fast for any longer than 12 hours overnight (18). 

Although it’s a myth that women need to ‘eat for two’, certain nutritional requirements do increase during pregnancy:

• Increased energy requirements: During the third trimester energy requirements increase by an estimated extra 200 kcals per day (18).
• Increased protein requirements: Protein intake is vital for foetal growth and development. In the UK, it is advised to increase protein requirements in pregnancy by an additional 6 g per day (19). Whereas the FAO, WHO and UN recommend that protein intake should be increased by 0.64g per day during the first trimester, 1.84g per day during the second trimester and 4.76g per day in the third trimester (20). For example, this would work out as an extra 3 almonds per day (1st trimester), 7 almonds per day (2nd trimester) and 18 almonds per day (3rd trimester).
• Increased carbohydrate requirements: Carbohydrates are essential for glucose metabolism and provide energy for both the mother and for the developing baby (21). In the US, pregnant women are advised to consume 175g per day of carbohydrates per day, as compared with 130g per day for non-pregnant women (22). Those who develop gestational diabetes should work closely with their healthcare team to understand how your requirements may differ during this time.
• Omega 3s: Omega 3s, such as EPA and DHA are essential polyunsaturated fatty acids that play a vital role in lipid metabolism, brain and nervous system development of the foetus. The European Food Safety Authority (EFSA) advise that pregnant women should consume an additional 100 – 200mg of DHA per day (23). Similarly, the US recommendation is an additional 300mg of omega 3 per day for pregnant women (23). The UK recommendation during pregnancy is to consume two portions of fish each week, one of which should be oily fish such as salmon, sardines, trout, herring and mackerel (24).
• Iodine: This mineral is key in foetal brain development and synthesis of thyroid hormones. The main dietary sources of iodine in the UK include: milk, yogurt, cod, haddock and scampi, therefore vegan and vegetarians may need to consider an iodine supplement (25). EFSA recommends that pregnant women should consume 200 mcg per day, which is 50 micrograms higher than for non-pregnant women (23). However, if taking a pregnancy multivitamin, this should not contain more than 150 mcg (25).
• Iron: This mineral plays an important role in transporting oxygen in the blood. This is key during pregnancy when the mother has an elevated red blood cell volume to support her needs, as well as her baby. Additionally, iron plays a role in foetal neurodevelopment so consuming the recommended amounts of iron is vital. Studies have even attributed iron deficiency anaemia to lower birth weight babies (26). Foods high in iron include meat, fish, beans, pulses, green leafy vegetables, fortified cereals and dried fruit like apricots and prunes.

As discussed in relation to prenatal nutrition, it is important to continue taking a folic acid supplement until the 12th week of pregnancy and a daily 10 microgram vitamin D supplement. It is also important to continue to avoid alcohol and limit caffeine to 200mg per day.  It is also advised to drink no more than four cups of herbal tea a day (17). 

There are some additional food safety considerations for pregnant women (17, 27):

• Avoid unpasteurised dairy and mould-ripened cheeses: This includes cheeses with white rinds, like brie, camembert and some types of goat’s cheese. This is to reduce the risk of food poisoning from a bacterial infection that can harm the foetus and increase the risk of miscarriage, called listeriosis.
• Avoid certain fish: Although consuming fish is recommended during pregnancy, high-mercury fish such as shark, marlin and swordfish have the potential to harm foetal development and should be avoided (28). Tuna also has quite a high mercury content, so should be limited to two tuna steaks, or four medium-size cans of tuna per week during pregnancy. Oily fish can contain other pollutants, so should be limited to two 140g portions per week.
• Avoid raw shellfish: As this can contain harmful bacteria, viruses or toxins that can result in food poisoning.
• Avoid raw or partially cooked eggs: This includes hen, duck, goose and quail eggs, or any foods containing raw or partially cooked eggs. Consuming raw or partially cooked eggs can increase the risk of salmonella food poisoning. However, eggs with a British Lion stamp can be consumed when raw or partially cooked during pregnancy, because they are less likely to contain salmonella.
• Avoid raw or undercooked meat: Meat should be cooked until there is no trace of pink or blood left and any cold cured meats (like prosciutto, salami, pepperoni and chorizo) should also be cooked thoroughly. This reduces the risk of getting an infection called toxoplasmosis which can increase the risk of miscarriage.
• Avoid liquorice root: This is advised as a precaution based on a study that found this may negatively impact foetal development (29).
• Avoid game meat: As this can contain a lead shot.
• Avoid a high intake of Vitamin A:. Excess vitamin A can be toxic to an unborn baby, therefore it is recommended to avoid any supplements that contain vitamin A as well as avoiding liver and l pâté, including vegetarian pâté. Retinol is a form of vitamin A found in skin care and acne products. Pregnant women (and those trying to conceive) are advised to avoid prescription acne drugs which contain high amounts of retinol as a precautionary measure.
• Pay particular attention to food hygiene: This includes washing fruit and vegetables thoroughly, washing hands, equipment and work surfaces well after handling raw food and ensuring any reheated food is piping hot all the way through. This reduces the risk of toxoplasmosis (21).

Depending on the symptoms a woman is experiencing at various stages of pregnancy, she may also need to make changes to her diet to account for: 

• Constipation: Thijs impacts nearly three quarters of women during the first trimester (30). Consuming plenty of fluids and increasing the intake of high-fibre foods such as wholemeal bread, pasta and rice, fruits and vegetables and some beans and pulses may help. Another option is adding some flaxseed to the diet, gradually building up to 1 tablespoon (and drinking lots of fluid). If taking iron supplements, you can speak to your health professional about whether this may be impacting your bowels (31).
• Nausea and vomiting: Many women have periods of nausea and vomiting throughout the first 16-20 weeks of pregnancy. Though there is no quick fix for this, but here are some tips for coping with morning sickness:
  • Eating smaller meals and snacks more frequently across the day.
  • Ensuring good fluid intake by sipping on water to prevent dehydration.
  • Opting for plain food without strong flavours or aromas.
  • There is some evidence to suggest that ginger can help with nausea during pregnancy (32).

If the vomiting is severe to the point where you are losing weight, unable to keep down food for over 24 hours or any other symptoms that are unusual, be sure to contact your midwife, GP or ring 111 if you live in the UK (33). 

• Heartburn: Eating little and often, avoiding foods that are spicy or high in fat and keeping your head slightly elevated whilst sleeping may help with reducing symptoms of heartburn. Most over the counter antacids are safe during pregnancy, however you should consult your GP to see what is appropriate for you (33).

Postnatal Nutrition

The body goes through a lot throughout pregnancy and giving birth, so it is important for mothers to take care of themselves after their baby is born, which includes aiming to consume a nutritious diet. There are no official guidelines for postnatal nutrition for those who are not breastfeeding, so in the UK the advice would be to follow The Eatwell Guide. But this will depend on each situation, for example, iron may be a concern if there was a lot of blood loss while giving birth. 

There are of course a lot of changes to adapt to when you are taking care of a newborn, particularly in terms of your daily routine and sleep. Therefore, meal and snack ideas will need to be realistic, quick and convenient. During this time it may help to make use of convenient options like bread, cereals, frozen, tinned, dried food and pre-prepared foods. 

If a mother chooses to breastfeed it is recommended to consume (35, 36, 37):  

• A balanced and varied diet based on The Eatwell Guide, being guided by your appetite and avoiding long gaps between meals.
• Plenty of fluids, like water or milk, and have a drink beside you when you are breastfeeding.
• At least two 140g portions of fish a week, including at least one portion of oily fish like salmon, mackerel, herring, trout or sardines. But oily fish should be limited to a maximum of two portions per week, and no more than one portion of shark, swordfish or marlin should be consumed due to the risk of certain pollutants building up in the breast milk.
• No more than 200mg of caffeine per day (the same advice as during pregnancy).
• No alcohol until your baby is at least 3 months old, then from 3 months and onwards only have an occasional drink with a meal, leaving 2 hours between drinking alcohol and breastfeeding.

Requirements also increase while breastfeeding for (22, 25): 

• Energy by roughly 500 kcals per day during the first 3-4 months of breastfeeding (38).
• Protein: by an extra 11 g of protein per day for the first 6 months of breastfeeding, and an extra 8g per day after 6 months.
• Calcium requirements increase by 550mg per day.
• Omega 3: Daily DHA requirements remain 100 – 200mg higher during breastfeeding as compared with pre-pregnancy.
• Iodine requirements remain at 200mg, which is 50mg higher than pre-pregnancy.
• Other vitamins such as: vitamin A, vitamin C, folate and certain B vitamins and choline (39).
• Other minerals such as: phosphorus, magnesium, selenium, copper and zinc.

It is also advised to consider taking a daily 10 microgram vitamin D supplement (especially from October to March) (40). Beyond this, it depends on whether there are any nutritional gaps in your diet to fill. For example, vegans and vegetarians may need to supplement with vitamin B12, vitamin D, omega 3 and iodine (35, 41). The Centers for Disease Control and Prevention (CDC) also recommends that breastfeeding mothers who follow a restrictive diet including “diets that limit the number of calories per day” supplement with vitamin B12 (35). If you are uncertain about whether you need to adapt your diet to meet your nutritional needs while breastfeeding, you can seek support from a Registered Dietitian. You should also speak with your doctor before starting any vitamins or supplements while breastfeeding. 

Consuming a variety of flavours, including a variety of vegetables, may also be beneficial, as these flavours have been found to pass to the baby via breast milk and this may impact the foods they will accept in future (42, 43).  

Speak with your GP or health visitor if you are concerned that your baby may be having a negative reaction to your breastmilk, or bring your baby to A&E if this seems urgent. You can also call the UK National Breastfeeding Helpline on: 0300 100 0212.

Summary:

There are important nutrition considerations to adopt before, during and after pregnancy. With the exception of increasing food safety specific to pregnancy, most of the focus during these life stages is on consuming a balanced and varied diet in line with the Eatwell Guide or the Mediterranean style diet. 

Please note: This article is for information and educational purposes only, please speak to a registered healthcare professional for individual advice.

Source: https://thefoodmedic.co.uk/2021/06/nutrition-during-pregnancy/