Increased risk in pregnancy for obese women, says study

Posted on: 09 June 2015

Women with obesity have increased risk in pregnancy compared with those in the healthy weight category, according to a new systematic review of research from academics at Trinity College Dublin, the University of Gothenburg, and City University London.

The paper, which is published in the journal Obesity Reviews recommends women with overweight or obesity should lose weight before they become pregnant, and also highlights the current lack of support present for these women.

Maternal obesity – defined as having a BMI over 30 kg/m2 when starting pregnancy compared to the healthy weight category of between 18.5 and 24.9 kg/m2 – is linked with adverse outcomes for mothers and babies. Problems can include gestational diabetes, high blood pressure, pre-eclampsia, depression, instrumental and caesarean birth, and surgical site infection, all of which are more likely to occur in pregnant women with obesity compared to women of healthy weight.

Maternal obesity is also linked to greater risk of pre-term birth, large-for-gestational-age babies, fetal defects, congenital anomalies, and perinatal death. Furthermore, breastfeeding initiation rates are lower and there is a greater risk of early breastfeeding cessation in women with obesity compared with healthy weight women.

To get a comprehensive insight into all risks related to obesity in pregnant women, the researchers produced a systematic overview of 22 systematic reviews, which looked at a total of 573 research studies comparing outcomes between pregnant women with obesity and those of healthy weight.

Professor Cecily Begley, author on the study and Chair of Nursing and Midwifery in Trinity College Dublin, said: “Our review has shown that women with a BMI of 30 or above – those with obesity – have higher risks in pregnancy compared to those with a healthy weight. They are more likely to have large babies, and less likely to have a normal birth. However, it is important not to stigmatise women because of their weight. We need to provide pre-conceptual health education, through national subsidised programmes, to support and encourage women with a high BMI to lose weight before they conceive. The benefits for them and their babies can be significant.”

The study has been welcomed by Professor Michael Turner, Clinical Lead for the National Clinical Programme in Obstetrics and Gynaecology, who has a keen interest in this area. “Our own research in Ireland has shown similar results,” he said. “The potential complications of obesity in pregnancy can lead to longer duration of hospital stay and greater costs. Given the high proportion of pregnant women with obesity (x% at present in Ireland), it is crucial to invest in weight loss support for these women, to reduce the risks for mothers and babies.”

One strand of Trinity College Dublin’s MAMMI study (Maternal health And Maternal Morbidity in Ireland), funded by the Health Research Board, is examining morbidities linked with obesity in pregnancy, with a view to developing new methods of support for women. More information on the MAMMI study is available from

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