Gaining too much or too little weight during pregnancy can harm both baby and mother, according to a paper - Association of Gestational Weight Gain With Maternal and Infant Outcomes: A Systematic Review and Meta-analysis - published on 6 June 2017 in the Journal of the American Medical Association.
What are the headlines from the research?
Researchers from Monash University in Melbourne, Australia, reviewed more than 1.3 million pregnancies, using data from Asia, the US and Europe. They found that 47 percent of pregnant women gained too much weight during pregnancy and 23 percent did not gain enough weight to meet recommended levels. Researchers found that women who gained too much weight were 85 per cent more likely to have an overly-large baby, and 30 per cent more like to require a C-section delivery. The 23 per cent of women who put on too little weight increased the risk of premature birth by 70 per cent.
They also found that 7% of women were underweight and 38% were overweight and obese at the time of pregnancy.
What are the guidelines on weight gain during pregnancy?
Well here's the thing: UK midwives do not have any guidelines on which to base their practice. This research focused on the guidelines published by the US’s Institute of Medicine in 2009. These recommend that: underweight women gain from 28 to 40 pounds during pregnancy; normal-weight women should gain between 25 and 35 pounds; overweight women should gain 15 to 25 pounds; and obese women should limit weight gain to 11 to 20 pounds.
What message do I take from this research?
I always have misgivings about blind dependence on the measure of 'weight' as it does not give an insight into the body's composition (particularly the split between muscle mass and fat mass, and the amount of water in the body) and therefore has its limitations. Those misgivings aside, this research clearly emphasises the need for monitoring and support strategies for women before and during pregnancy.
What have other experts said about this research?
Dr Daghni Rajasingam, spokesman for the Royal College of Obstetricians and Gynaecologists, said: 'These findings have relevance in the UK as one in five pregnant women are obese and illustrate the importance of maintaining a healthy lifestyle through a well-balanced diet and exercise before, during and after their pregnancy to reduce associated complications...Having a normal bodyweight will help to increase the chances of conceiving naturally and reduces the risk of pregnancy and birth complications for the mother and baby.'
Louise Silverton, director for midwifery at the Royal College of Midwives, said: 'This is very useful research that underlines even more the importance for women, and their babies, of being a healthy weight before and during pregnancy...This study shows how important it is for women to avoid gaining excessive weight during pregnancy and, if overweight at the end of pregnancy, to try to lose that weight before they have another baby."
How can we better support women?
We need to educate women. The days of confinement and bed rest for those having healthy pregnancies are over. Eating for two is not necessary: a woman's energy needs do not change until the last three months of pregnancy, when women need to consume only an extra 200 calories a day. Women need support in understanding the importance and benefits of healthy eating and staying active in pregnancy and, moreover, how to achieve this. I recognise that for many women, the prospect of changing shape and gaining weight during pregnancy is overwhelming and terrifying. Encouraging and educating women to embrace a healthy lifestyle before conception and throughout pregnancy - rather than focusing solely on the number on the scales - is, for me, perhaps a gentler, more positive and more sustainable approach.
Alongside this approach, it would also be helpful and sensible for those providing antenatal care to monitor women's weight through pregnancy, though I recognise that GPs and midwives are already stretched to capacity. NICE guidance is to weigh women at the start of pregnancy and only to re-weigh if there are concerns. This approach has its shortcomings where there is no continuity of care throughout pregnancy. Finally, introducing UK guidelines on weight gain during pregnancy and discussing these with women during antenatal and pre-conception care seems like a sensible way to help women to understand what is too much and what is too little based on their own starting point.