Diabetic mothers and risk of birth defects in baby: Study

By Dr. Ananya Mandal, MDFeb 6 2012

A new study published in Diabetologica reveals that pregnant women with diabetes are almost four times more likely to have a baby with a birth defect.

The study researchers noted a higher risk of infants suffering serious problems if their mothers had Type 1 or Type 2 diabetes, compared with women without the condition. The range of birth defects included problems with the nervous system (such as spina bifida), digestive, musculoskeletal and cardiovascular defects and urinary disease.

Researchers led by Ruth Bell from Newcastle University reached their conclusions after studying 401,149 single-baby pregnancies between 1996 and 2008 in the north of England, 1,677 of them pregnancies of diabetics.

It also found that women with diabetes had no higher risk of having a baby with a chromosomal abnormality such as Down's syndrome, and these conditions were excluded from the analysis. Diabetes that occurs during pregnancy, known gestational diabetes, was also excluded.

Diabetics had a 7 per cent risk of a having a baby with a birth defect, compared with about 2 per cent in women without diabetes they note. The chance of a birth defect was lowest in women who had blood glucose levels within the normal range at the start of pregnancy. For women with Type 1 diabetes, the chance of a birth defect was 82.2 per 1,000 pregnancies and 57.9 per 1,000 in women with Type 2, which is linked to unhealthy lifestyles and obesity. Overall, women with diabetes had a 3.8 times higher risk of having a baby with a defect. Diabetic women from poorer backgrounds, or who did not take folic acid, were at higher risk, they found.

Iain Frame, the research director at Diabetes UK, which funded the study, said it had identified that the mother's blood glucose level at time of conception was related to her risk of having a baby with a birth defect, such as a heart abnormality. Diabetic women considering becoming pregnant should alert their medical team so that steps can be taken to minimize the risk. In addition, women who are diabetic should make sure to use contraception so that they do not become pregnant unexpectedly, Frame said. This is because some drugs taken by Type 2 diabetics – 90% of the UK's 2.9 million patients diagnosed with the disease – can cause problems for a developing fetus, and in such cases the women need to take higher than usual doses of folic acid, he said.

“Although it has been known for some time that maternal diabetes is associated with an increased risk of fetal anomalies, this study has, for the first time, quantified the relative risk,” said Justin Warner clinical lead for the National Pediatric Diabetes Audit, which is led by the Royal College of Pediatrics and Child Health. “This highlights the importance of good diabetes control in mothers at the time of conception and the need for careful diabetes monitoring if pregnancy is being considered.” Young women with diabetes need to be educated about the risk of having a child with an abnormality if they become pregnant, he said.

Women with diabetes do get offered specialist preconception care, “but uptake remains low, and women from ethnic minority groups, socially deprived areas, and with Type 2 diabetes are less likely to attend”, the study says.

A Department of Health spokeswoman said, “We know that diabetes brings increased risk of complications during pregnancy and that the best way to avoid the complications is through good planning and making sure that the diabetes is well controlled before and during pregnancy.” The Change4Life campaign was encouraging people to adopt healthier lifestyles, which would help prevent diseases such as diabetes in the first place, she added.

Dr Ruth Bell, the study's lead researcher, from Newcastle University and Newcastle's Regional Maternity Survey Office, said, “The good news is that, with expert help before and during pregnancy, most women with diabetes will have a healthy baby. The risk of problems can be reduced by taking extra care to have the best possible glucose control before becoming pregnant. Any reduction in high glucose levels is likely to improve the chances of a healthy baby.”

Around 300,000 people in the UK have Type 1 diabetes, which usually develops under the age of 40 and requires daily insulin injections. Another 2.6 million are diagnosed with Type 2, which is linked to unhealthy lifestyles and obesity. It is estimated there are also 850,000 people with undiagnosed Type 2.