LONDON, 10 August 2012 (IRIN) - Making sure expectant mothers eat enough remains the main concern of health workers, especially in poorer rural areas of sub-Saharan Africa, but this concentration has masked the fact that some pregnant women are dangerously overweight.

Swaziland, the fattest country in Africa, now has a maternal obesity rate of 27 percent, and an additional 32 percent are overweight - levels comparable to those in Europe. In the UK, for instance, around half of pregnant women either overweight or obese.

National figures conceal great variation within countries, with the obesity rates estimated to be three times higher in urban areas than in rural ones. In many cities, this is a visible epidemic, and the causes are visible too. Main streets in Nigeria's cities are now lined with fast food outlets such as Mr Biggs and Chicken Republic. Nigeria's national maternal obesity figures - 17 percent overweight and 6 percent obese - will conceal much higher rates among certain groups of women.

Being overweight is a known risk in pregnancy, and Jenny Cresswell, an epidemiologist at the London School of Hygiene and Tropical Medicine, has set out to track the consequences of these growing obesity rates on child survival.

Using the existing data in the demographic and health surveys compiled by ORC Macro on behalf of the US Agency for International Development (USAID), Cresswell and her colleagues looked at figures from 27 countries in sub-Saharan Africa and found that babies born to overweight and obese mothers were at significantly increased risk of neonatal death compared with those born to those to optimum-weight mothers. Surprisingly, they found no increased risk of neonatal death for the babies of underweight mothers, even though that has been a traditional cause of concern.

Need for more data

"The biggest limitation in the data was that height and weight were recorded at one point in time, after a woman's pregnancy, whereas ideally we would measure then before or early in her pregnancy, but there is currently no data that would allow us to do that. Even so, we are confident in concluding that there is a true association," Cresswell told IRIN.

While clear, the association with neonatal death is less marked than in more developed countries. In a paper published this week in the medical journal the Lancet, the team suggest that this may simply be because very overweight women in sub-Saharan Africa rarely reach the extremes of morbid obesity (considered to be a body mass index of 40 kg/cu.m and above) increasingly seen in Europe and North America.

The raw statistics record when a woman's baby has died, and how long after birth, but they don't give the cause. "We do need more robust research, especially on the causes of death," Cresswell told IRIN. "A large part of the effect is likely to be due to unmeasured diabetes. And if that is truly the case, then we know how to treat diabetes."

Ellen Nohr, an epidemiologist at Aarhus University in Denmark, hails the finding as important, despite the fact that Cresswell's team was working with less-than-perfect data. Fuller studies, she said, could reveal causes that are easily prevented if obese women are screened for diseases during pregnancy, and delivered in a facility with emergency obstetric and neonatal care. But, she added, "The world can't just wait for better data."

Encouragingly, the findings show that once healthcare professionals are alert to the issue, simple and inexpensive interventions can help a lot. Body mass indices can be established with scales and a measuring rod. Overweight women can also be advised on reducing their weight during pregnancy and encouraged to have their babies in a clinic with the necessary facilities.

As Cresswell says, "In general it is the wealthier women and the more educated women who are more likely to be overweight, so if given this advice during antenatal care, it is reasonable to assume that many of these women will have the capacity to act on it.

"Nutritionists generally talk about obesity in terms of things like cardiovascular problems, which show themselves later in life. But talking to a woman about risks to her baby may be more of an incentive to maintain a healthy weight than saying, 'You will get ill in twenty years time.'"

Source:  Integrated Regional Information Networks (http://www.irinnews.org )