The Mummy's Club

The importance of the guidelines is borne out by figures suggesting that more pregnant women than ever are overweight or obese. The Guardian suggests that, “15-20% of women getting pregnant are overweight or obese”. The Daily Mail puts the number higher, saying that “almost half of expectant mothers are overweight or obese”. It goes on to spell out the dangers of being obese or overweight during pregnancy, which include “fatal health conditions such as blood clots, pre-eclampsia, miscarriages and stillbirths”.

The newspapers also dispel the myth that women should eat for two during pregnancy. Further advice reported in the press includes taking at least 30 minutes of moderate exercise per day during pregnancy, and that pregnant women should avoid dieting and only need to have an extra 200 calories a day in the last three months of their pregnancy.

These guidelines are published by NICE, and are evidence-based. They are designed so that doctors can give women up-to-date reliable advice to follow to maintain a healthy weight before, during and after their pregnancy.

Where did the advice come from?

The advice has just been published by the National Institute for Health and Clinical Excellence (NICE) as part of its public health programme. NICE produces guidance on the promotion of good health and the prevention of ill health for those working in the NHS, local authorities and the wider public and voluntary sector.

What are the health risks of being obese during pregnancy?

Women who are obese (with a BMI over 30) when they become pregnant face an increased risk of complications such as diabetes, miscarriage, pre-eclampsia, blood clots and death. Obese women are also more likely to have an induced or longer labour, post-delivery bleeding and slower wound healing after delivery. They also tend to be less mobile, which can result in a need for more pain-relieving drugs during labour. These can be difficult to administer in obese women, resulting in a greater need for general anaesthesia with its associated risks.

For women who have gained weight between pregnancies, even a relatively small gain of 1-2 BMI units can increase the risk of high blood pressure or diabetes during their next pregnancy and may also increase the chance of giving birth to a large baby.

What sort of diet does NICE recommend?

NICE offers the following dietary advice to help women to achieve and maintain a healthy weight:

• Base meals on starchy foods (such as potatoes, bread, rice and pasta), choosing wholegrain where possible.
• Eat foods rich in fibre.
• Eat at least five portions of fruit and vegetables per day in place of foods higher in fat or calories.
• Eat as little as possible of fried foods, and drinks and confectionery high in sugars and fats.
• Eat breakfast.
• Watch portion size of meals and how often they are eaten.

What should women aim to weigh before getting pregnant?

Women with a BMI of 30 or more can achieve significant health benefits if they lose between 5-10% of their weight. Further weight loss to achieve a BMI within the healthy range of 18.5 and 24.9 is encouraged.

What about weight during pregnancy?

The amount of weight a woman may gain in pregnancy varies a great deal, and only some of it is due to increased body fat. The unborn child, placenta, amniotic fluid and increases in maternal blood and fluid volume all contribute to weight gain during pregnancy.

• Dieting during pregnancy is not recommended as it may harm the health of the child.
• There is no need to ‘eat for two’ or drink full-fat milk (as opposed to lower-fat milk). Energy needs do not change in the first six months of pregnancy. Only in the last three months do a woman’s energy needs increase by around 200 calories per day.
• Moderate-intensity physical activity will not harm the mother or baby. At least 30 minutes per day of moderate intensity activity is recommended. This can include activities such as swimming or brisk walking. If women have not exercised routinely up to that point, they should begin with no more than three 15-minute sessions a week, increasing gradually to daily 30-minute sessions.
• There are no formal evidence-based guidelines from the UK Government or professional bodies on what constitutes appropriate weight gain during pregnancy.

How do I safely lose weight after giving birth?

Women are encouraged to breastfeed, but are advised against dieting while breastfeeding. Women who feed their babies with breastmilk only for the first six months may require an additional 330 calories a day, but this may differ between individuals, and some of these additional calories will be derived from fat stores built up during pregnancy.

If the pregnancy and delivery are uncomplicated, mothers may start a mild exercise programme consisting of walking, pelvic floor exercises and stretching immediately after giving birth, but women should not resume high-impact activity too soon. Women who have had complicated deliveries or caesareans should not resume pre-pregnancy levels of physical activity before consulting their medical caregiver.

Health professionals should be able to provide details of appropriate community-based services for women who want support to lose weight.

Where can I get more information?

Women should consult their GP or midwife about maintaining a healthy lifestyle before, after and during their pregnancy.

Links To The Headlines

Mothers must lose baby weight before getting pregnant again, NICE says. The Daily Telegraph, July 28 2010

Weight, exercise and pregnancy confusion. BBC News, July 28 2010

Mothers who lose weight before further pregnancy ‘reduce risks’. The Guardian, July 28 2010

Don’t eat for two, pregnant mothers are told amid obesity fears. Daily Mail, July 28 2010

This Danish research has analysed the pregnancy drinking habits of 347 women during pregnancy and the quality of their adult sons’ semen. Although the study found a relationship between higher alcohol consumption and lower sperm concentration, semen volume and total sperm count, the trend and its implications are not completely clear. There are numerous limitations to the research, such as the small number of participants and the adaptation of a study design originally devised to examine smoking. Crucially though, male fertility was not directly assessed, meaning it is incorrect to assume that the men involved would have difficulties if they try to father children.

Overall, there are no definite conclusions to draw from this limited research. However, regardless of the study’s limitations, pregnant women are strongly advised to limit or avoid alcohol during pregnancy due to the numerous established harmful effects of excess alcohol during pregnancy.

Where did the story come from?

The study was carried out by researchers from Aarhus University Hospital, Denmark, and funded by Danish Medical Research Council. The study was published in the peer-reviewed medical journal, Human Reproduction.

News reports have reflected the findings of this research, but have generally not taken into account several of the study’s important limitations. This means that no firm conclusions can be drawn on this issue. The Daily Mail’s opening paragraph, which says that ‘pregnant women who drink alcohol could be jeopardising their chances of becoming grandmothers,’ is not substantiated by this research or supported by the researchers.

What kind of research was this?

This was a cohort study that aimed to investigate the effects of exposing a male foetus to alcohol. Specifically, it looked at what effect maternal alcohol consumption during pregnancy has upon sperm quality and levels of reproductive hormones once the child has reached adulthood.

A cohort study is the best design for examining the relationship between a cause (maternal alcohol) and potential effect (reduced fertility in the son). However, to ensure the accuracy of its results a cohort study must take into account all possible confounders that could affect the relationship being studies. A limitation of this particular study is that it was not set up to examine the link between maternal alcohol consumption during pregnancy and sperm quality in the son. The original aim and design was an examination of the effect of smoking in pregnancy on sperm quality.

What did the research involve?

This research used participants of a Danish cohort study (the Healthy Habits for Two study), which recruited 11,980 pregnant women between 1984 and 1987. At 36 weeks of pregnancy the women completed a questionnaire on their lifestyle habits including drinking of beer, wine and spirits. Responses were categorised as drinks per week (for each drink type): never, 1, 1-4, 5-9, 10-14, 15-19, 20 or more.

After summing the total of each type of drink, they put each woman into a category of: less than one drink a week, one to 1.5 drinks a week, two to four drinks, or 4.5 or more drinks a week. One standard drink in Denmark reportedly corresponded to 12g of pure alcohol. In the UK, one standard drink (unit) contains 8g of pure alcohol.

In 2004, a total of 5,109 sons were identified through the Danish Civil Registration System. Between 2005 and 2006, the researchers collected semen samples from 347 men (48.5% of the 716 invited to participate) and took blood samples (both performed with due laboratory protocols). They analysed semen for sperm concentration and motility, and looked at hormone concentrations in the sample.

The men also provided questionnaires containing health and lifestyle questions, including about their own alcohol consumption. When calculating the associations between maternal alcohol and semen quality the researchers adjusted for maternal smoking, and in the sperm donor’s, smoking, alcohol, history of reproduction infections/disease, and days of sexual abstinence prior to providing the sample.

What were the basic results?

Of the mothers of the 347 men who participated in the study, 110 drank less than one drink a week during pregnancy, 127 had one to 1.5 drinks a week, 72 women had two to four drinks a week, and 38 drank 4.5 or more drinks a week.

There was a trend for decreasing sperm concentration with increasing alcohol exposure while in the uterus. The researchers calculated that sons of mothers who were in the highest alcohol category during pregnancy (more than 4.5 drinks a week) had a 32% lower sperm concentration than those whose mothers were in the lowest category (less than one drink a week).

Maternal alcohol consumption showed no clear relationship with either semen volume or total sperm count (the 1-1.5 drinks per week group was associated with the highest volume and sperm count). There was no observed association between maternal alcohol consumption and hormone levels, sperm motility or sperm morphology. They also found that higher pregnancy alcohol consumption was independently associated with the mum being of lower BMI, being of older age and being a smoker, and with the son being of lower birth weight.

How did the researchers interpret the results?

The researchers conclude that their results indicate that prenatal exposure to alcohol may have an adverse effect on sperm production, and if this were a causal relationship it could explain some of the reported differences in semen quality between populations and across generations.

Conclusion

This research has found some association between semen quality in sons and their mothers’ alcohol consumption during pregnancy. However, there are several important limitations to this research:

• As the researchers say, ‘the participants were selected according to levels of maternal smoking during pregnancy’. Carrying out a post hoc analysis that was not the primary aim of the study increases the risk of chance findings. This may be particularly problematic in this instance as the initial research had a preference for selecting women who smoked and therefore may not have been a typical representative sample of pregnant women.
• Although the cohort of pregnant women was very large (11,980), there were only a total of 347 sets of mothers and sons across the four categories of alcohol consumption analysed. With this small number there is a high possibility of chance findings, particularly with the association found for drinking more than 4.5 drinks a week as there were only 38 women and their sons in this category. The findings based on the analyses of these small numbers may be by chance.
• Additionally, only half of the men invited to participate chose to do so. There may be important differences between the population studied and those who chose not to participate.
• An association was found between higher and drink consumption and decreasing sperm concentration, semen volume and sperm count. However, these relationships were not completely clear, with the highest values being in sons of mothers who drank 1-1.5 drinks a week rather than in those who drank more or less than this. There was also no relationship with hormone levels, sperm motility or sperm morphology. Therefore the actual implications of these findings are not clear.
• It is not known whether any of the differences in sperm quality seen across the groups would cause any actual fertility problems for the man.
• Alcohol consumption was assessed at the end of pregnancy. It is unclear whether the answer reflected the whole of the pregnancy, or just at the time of assessment. Also with any assessment like this, the number of drinks and size and strength of a drink will mean different things to different people.
• There is a possibility that other confounders have not been adjusted for or not fully adjusted. For example, the reporting of alcohol consumption by the men themselves was adjusted for but there may have been insufficient data to do this reliably.

Regardless of the limitations of this research and uncertainty over its findings, there are numerous other established harmful effects of consuming alcohol during pregnancy. NICE recommendations on alcohol consumption (based on one unit being 8g of pure alcohol instead of the 12g used in this study) during pregnancy advise that:

• Pregnant women and women planning a pregnancy should avoid drinking alcohol in the first three months of pregnancy because it may be associated with an increased risk of miscarriage.
• If women choose to drink alcohol during pregnancy they should be advised to drink no more than 1 to 2 UK units once or twice a week (1 unit equals half a pint of ordinary strength lager or beer, or one shot [25ml] of spirits. One small [125ml] glass of wine is equal to 1.5 UK units). Although there is uncertainty regarding a safe level of alcohol consumption in pregnancy, at this low level there is no evidence of harm to the unborn baby.
• Women should be informed that getting drunk or binge drinking during pregnancy (defined as more than five standard drinks or 7.5 UK units on a single occasion) may be harmful to the unborn baby.

Links To The Headlines

Pregnant drinking ‘affects sperm’. BBC News, 30 June 2010

Pregnant women who drink alchohol may reduce the sperm count of sons. The Guardian, 30 June 2010

Women who drink alcohol during pregnancy ‘could damage their sons’ fertility’. Daily Mail, 30 June 2010