Weight Loss Blog

Obese pregnant women are at increased risk of having a baby with a congenital heart defect, a new study finds.

On average, obesity is associated with a 15 percent increased risk of having a baby with a heart defect. But the risk rises with the level of obesity. Compared to normal-weight women, the risk is 11 percent higher in moderately obese women and 33 percent higher in morbidly obese women.

In general, women who were overweight but not obese had no increased risk, said the researchers at the U.S. National Institute of Child Health and Human Development (NICHD) and the New York State Department of Health.

“The trend is unmistakable: the more obese a woman is, the more likely she is to have had a child with a heart defect,” study first author Dr. James L. Mills, of the NICHD’s Division of Epidemiology, Statistics and Prevention Research, said in a news release.

The study was published online April 7 in the American Journal of Clinical Nutrition.

“The current findings strongly suggest that by losing weight before they become pregnant, obese women may reduce the chances that their infants will be born with heart defects,” Dr. Alan E. Guttmacher, acting director of the NICHD, said in the news release.

For this study, researchers compared the records of mothers of 7,392 children born with major heart defects and more than 56,000 mothers of infants born without birth defects. Because the study looked at the records of infants after they were born, it doesn’t conclusively prove that obese women who lose weight before becoming pregnant will reduce their risk of having a baby with a heart defect, the researchers noted.

However, “if a woman is obese, it makes sense for her to try to lose weight before becoming pregnant,” Mills said. “Not only will weight loss improve her own health and that of her infant, it is likely to have the added benefit of reducing the infant’s risk for heart defects.”

Warning over obesity in pregnancy

Medical experts call for all mothers-to-be to be weighed regularly throughout their pregnancies due to health fears

All mothers-to-be should be weighed regularly during pregnancy to help combat the many dangers to women’s and babies’ health from maternal obesity, a group of medical experts is urging.

The National Obesity Forum (NOF) – an influential group of doctors and nurses specialising in weight problems – wants ministers to introduce the change because excessive weight gain among expectant mothers is becoming such a serious problem.

“A pregnant woman should have her weight monitored regularly during pregnancy at all antenatal appointments with midwives, GPs and obstetricians, because every risk of pregnancy, both to the mother and to the baby, is increased with maternal obesity,” Dr David Haslam, the NOF’s chairman, told the Observer.

“Obesity in pregnant women can lead to all sorts of problems, including the death of the mother, or the death of the baby through stillbirth or the baby having foetal abnormalities, or the woman suffering pre-eclampsia or gestational diabetes, or needing a Caesarean section because either she or the baby is too big,” he added.

Piling on the pounds in pregnancy beyond the recommended amount can be dangerous, Haslam said. “The risk of rapid weight gain in pregnancy is that every single complication of pregnancy gets worse for both the mother and the baby. The benefits of regular weighing of women would be enormous. It would create awareness of the problem and lead to measures being put in place to reduce the risk.” For example, if a pregnant woman was gaining excess weight, a dietician could start giving her advice on her diet and level of physical activity, said Haslam, who is a GP and also a hospital doctor specialising in obesity medicine at the Luton and Dunstable Hospital in Bedfordshire.

At the moment women in England have their height and weight taken when they have their first antenatal appointment, the so-called “booking visit”, in order to indicate their Body Mass Index (BMI). Only those with a high BMI are usually checked after that.

Many women would find the idea upsetting, patronising or offensive, admitted Haslam. “Yes, women will undoubtedly think this is intrusive, but that’s ridiculous because this would be being done for medical reasons, to protect the health of the mother and baby. It’s possible that some women will be against this, and they would have the right not to stand on the scales. But they would be foolish to refuse,” he added. “To refuse to be weighed would be to deny the clinician the tools of his trade to ensure a healthy outcome to the pregnancy.”

The NOF’s stance has divided medical opinion. Dr Anne Dornhorst, an expert in diabetes and pregnancy at Imperial College London and a doctor at the capital’s Hammersmith Hospital, said she understood why Haslam and the NOF were urging firmer action to counter maternal obesity. She pointed to the Centre for Maternal and Child Enquiries’ reference to “substantial evidence that obesity in pregnancy contributes to increased morbidity and mortality for both mother and baby”.

That includes evidence that 35% of women who die in childbirth are obese – they had a BMI of at least 30. About 30% of pregnant women are overweight or obese.

Obese women spend 4.83 more days in hospital than other new mothers. Babies whose mothers are obese are also 3.5 times more likely to need to be admitted to a neonatal intensive care unit.

“There’s a large body of thought out there that childbirth is completely natural and shouldn’t be medicalised. But we know that obesity is a danger for the pregnancy and that it influences the baby’s growth and risk of obesity in later life,” said Dornhorst, who favoured regular weighing of all overweight and underweight expectant mothers rather than all pregnant women.

But Janet Fyle, midwifery adviser to the Royal College of Midwives, said it would be “counter-productive” to change the current practice because women with very high BMIs were already identified and given extra monitoring if necessary.

A spokeswoman for the Royal College of Obstetricians and Gynaecologists agreed, saying: “Obesity is identified as a risk factor at time of booking and a referral is made appropriately. As per the National Institute for Heath and Clinical Excellence (NICE) antenatal care guidelines, there is no compelling evidence for routine weighing of all women at every visit.”

Pregnant women, parents and toddlers are the targets of a new government healthy lifestyles campaign, launched last week, called Start4Life. It involves promotion of breastfeeding and advice on when to start babies on solid food. But the NOF believes that far more extensive measures are needed.

In 2008 NICE, which advises the NHS on what treatments and procedures are worthwhile, said only mothers-to-be whose weight might lead to medical complications should be assessed regularly. Two of NICE’s working groups are currently investigating problems associated with weight and pregnancy, one on weight gain during pregnancy, the other on weight loss after pregnancy. It will distil their advice into a new set of guidelines for NHS staff to follow in a few months’ time.

A Department of Health (DH) spokesman ruled out introducing routine regular weighing. “NICE antenatal care guidelines state that normal weight and height should be measured at the booking appointment and the woman’s body mass index should be calculated. The guidelines say that repeated weighing during pregnancy should be confined to circumstances in which clinical management is likely to be influenced,” he said.