Nutrition in Pregnancy


Published: 08 September 2020

Pregnancy nutrition is a topic that can easily be overlooked, yet it plays a crucial role in maternal health as well as foetal and infant wellbeing (Walsh and McAuliffe 2015).

Midwives are ideally placed to provide education on nutrition during pregnancy, but to date, there is very little published research evaluating midwives’ knowledge, attitudes and confidence on the subject. What little research there is tends to be exploratory and descriptive and suggests that midwives lack basic knowledge of nutritional requirements.

One study that stands out in particular, however, suggests that whilst midwives’ attitudes towards educating pregnant women about nutrition are positive, their knowledge and confidence do not align with these attitudes.

As Arrish, Yeatman and Williamson (2016) suggest, this is most likely due to a lack of education during training, along with very few continuing professional development resources that focus on pregnancy nutrition.

Eating For Two

One of the many myths surrounding pregnancy is that a pregnant woman should be ‘eating for two’. Many studies are now suggesting that this is a myth that should be dispelled, at least for the first two trimesters of pregnancy, as the body adapts to absorb more energy from the same amount of food (RCOG 2015).

It is only in the last 12 weeks that women need an extra 200 calories per day for appropriate weight gain. Williamson (2006) does qualify this, however, by suggesting that this assumes a reduction in the level of physical activity during pregnancy and women who are underweight or who do not reduce their activity level may require more than this.

pregnant woman eating breakfast

Healthy Weight Management

Williamson (2006) also notes that well-nourished women with a normal pre-pregnancy body weight can still show wide variations in weight gain during pregnancy. Although there are no official UK guidelines, women with a healthy pre-pregnancy weight gain on average 12 kg throughout their pregnancy. This range of 10 to 14 kg is associated with the lowest risk of complications and a reduced risk of having a low birth weight baby. In practice, most countries use the following guidelines:

  • Women who are underweight are recommended to gain between 28 and 40 lbs (13 to 18 kg).
  • Women in the normal weight range are recommended to gain between 25 and 35 lbs (11 to 16 kg).
  • Women who are overweight may need to gain only 15 to 25 lbs during pregnancy (7 to 11kg).

(Tommy's 2018)

As Hull et al. (2020) report, interventions to prevent excessive gestational weight gain seem to have limited success. However, a recent study exploring the effectiveness of having a single goal of eating a high fibre diet resulted in less weight gain, and less retained weight at one year postpartum. It’s an area that seems deserving of much greater attention and research in the future.

Many organisations such as the Royal College of Midwives and Slimming World are also now calling for clearer guidance on healthy weight management for expectant mothers, along with more support, training and equipment for midwives to avoid the consequences of both excessive and low gestational weight gain (RCM 2018).

For example, recent NHS data shows that one in five women (21%) start pregnancy with a body mass index (BMI) in the ‘obese’ range, which is linked to increased risk of miscarriage, premature birth, gestational diabetes, stillbirth and other serious health issues (RCM 2018).

Conversely, low gestational weight gain can increase the risk of having a low birth weight baby, yet there are no national guidelines for women, midwives or health professionals on weight management during pregnancy.

Foods to Avoid During Pregnancy

Raw shellfish such as oysters should be limited or avoided altogether during pregnancy.

According to Williamson (2006), food safety issues including food hygiene and knowing which foods could be harmful should also be a part of both pre-conceptual care as well as antenatal care.

Some foods should be avoided altogether or strictly limited during pregnancy because of their potential to cause harm to either mother or baby, such as:

  • Miscarriage;
  • Food poisoning;
  • Hormonal imbalance; and
  • Harm to the fetus.

(NICE 2015)

In general, the following foods should be limited or avoided altogether during pregnancy:

  • Rare or undercooked meat. Meat should be well cooked because of the potential risk of toxoplasmosis.
  • Raw shellfish such as oysters.
  • Cured meats such as salami, pepperoni or Parma ham, unless they have been cooked.
  • Unpasteurised milk, yoghurt or cheese, including Brie, Camembert or veined blue cheeses.
  • Swordfish, marlin and tuna in large amounts. These fish contain mercury, which, if consumed in high levels can be harmful.
  • Liver and liver products such as pâté. These contain vitamin A which can be harmful to the fetus in large amounts.

(Aptamil 2020)

Pregnancy Pica

Another feature of pregnancy nutrition that tends to be under-reported is pregnancy pica. Pica describes a compulsive craving for non-nutritive substances such as earth, clay, chalk, soap and ice during pregnancy and its presence often goes unacknowledged. Sometimes dismissed as just a myth, Corbett, Ryan and Weinrich (2003) suggest that not only does pica exist, it may very well be more common than many healthcare providers realise. This is important for two reasons. Firstly, it can lead to nutritional imbalances. Secondly, if it is not recognised, it can lead to important information being missed during routine antenatal visits.

Young (2010) notes that there are multiple proposed aetiologies for pica including cultural expectations, psychological stress, hunger, dyspepsia and micronutrient deficiencies, particularly of iron, zinc and calcium.

One of the most popular theories is that pica is associated with severe anaemia or iron deficiency during pregnancy (Mikkelsen, Andersen and Olsen 2006).

As Corbett, Ryan and Weinrich (2003) point out, diagnosis is easy and simply involves non-judgemental questioning about a woman’s diet during an antenatal visit. It’s a simple step that could contribute to detecting nutritional deficiencies before any lasting harm is done.


pregnant woman at appointment

Perhaps it’s because of a lack of in-depth training in pregnancy nutrition, or a lack of time during antenatal visits, or even the perception that there is already an abundance of nutritional advice on the internet and in magazines, but whatever the reason, healthy lifestyle and nutritional advice do not always seem to get the attention they deserve.

Perhaps as the Royal College of Midwives (2018) suggested recently, this is a significant missed opportunity to share healthy lifestyle messages and nutritional guidance during pregnancy.