Please could you tell us a little bit about maternal obesity? Why is it projected to increase in sub-Saharan Africa over the next two decades?
I think it is important to say that levels of maternal obesity in sub-Saharan Africa are low by global standards, but obesity is projected to increase over the next two decades. The chief reason for this is because of urbanisation.
Although from a low base, Africa is urbanising quite rapidly. The UN predicts that the urban population will triple by 2050. When people move to an urban area, they tend to make lifestyle changes. For example, physical activity tends to drop, and the energy to cost ratio of food tends to become more important. People tend to start eating foods that are higher in fat and sugar.
How does maternal obesity in sub-Saharan Africa compare to rates in other countries in the world?
Maternal obesity rates in sub-Saharan Africa are low compared to other countries in the world. There is, however, huge variation across sub-Saharan Africa.
In Ethiopia there is less than 1% obesity. This is the same as in Madagascar. Whereas in Swaziland 27% of women were obese, this is almost identical to the current rates in England.
In southern Africa you are approaching European levels; whereas in Eastern Africa and further north the levels are low.
Your recent research indicated that the risk of neonatal death increased with maternal obesity. Please could you give us a brief introduction to neonatal death and who it affects?
A neonatal death is the death of an infant, who is born alive, within the first 28 days of life.
Neonatal death is primarily a problem of low or middle income countries. About 99% of all neonatal deaths occur in low or middle income countries.
The burden is highest in sub-Saharan Africa. It is roughly estimated that there are around 44 deaths per 1000 live births.
What do you think are the reasons why neonatal death increased with maternal obesity?
In this particular study we did not have cause of death data so this is speculation to a certain extent. There is good data from high income countries on the mechanisms and these include things like:
- Increased pre-eclampsia and hypertension in obese mothers
- Lower uterine contractility in obese mothers – this means the uterus is less effective during labour which causes prolonged labour which can harm the child
- Infants may be macrosomic – this means the baby tends to be larger (about 4,000 grams), this also increases the risk of a prolonged labour
In this particular study, an important reason is probably maternal diabetes. In antenatal care in Africa, mothers are not often tested for diabetes. We know, however, that maternal obesity is a very important risk factor for diabetes.
Diabetes, particularly when it is untreated, has a lot of potential severe implications for the infant, such as congenital abnormalities.
Thus, a lot of our findings may be due to maternal diabetes; however, we were unable to measure this in our study.
What further research is planned to determine these reasons?
No research is currently planned as we would first need further funding.
The ideal follow-up study would need to be quite large, as neonatal death is a relatively rare event. The study would also need to be prospective, so that you could get pre-pregnancy BMI. Also the study would need to get detailed cause of death – this would require being in the hospital at the time of death.
The ideal study would therefore be quite expensive.
Is this research applicable to all countries, i.e. does maternal obesity increase the risk of neonatal death in all countries, or are there other contributory factors found in sub-Saharan Africa that are not found elsewhere?
The association between maternal obesity and neonatal death is already a well-established phenomenon. There is quite a lot of good-quality evidence from high-income countries of a very similar association.
The novel thing about this study is that it is the first time the association has been found in Africa.
What other factors contribute to neonatal death?
Particularly in the sub-Saharan context, an important factor is quality of care. Neonatal intensive care units are more expensive to run, they need a lot of high quality equipment and specially trained people. These are not generally a priority given the other competing health problems.
There are also factors that we often don’t even think about – for example, if you have a baby that is born early or is very sick, then it needs to be in an incubator. An incubator requires a reliable electricity supply. This is not necessarily that prevalent in a lot of African hospitals.
One of the worrying things about this study is that babies that would survive in a high-income context are more likely to die in Africa, just because they don’t get that quality of care.
Are there plans in place to reduce maternal obesity and other factors that raise the risk of neonatal death?
There aren’t any plans that I am aware of, but research on preventative strategies is definitely an important focus. It is a research priority.
We hope that one of the contributions that our study will make is raising the problems of maternal obesity in low income settings. I don’t think it is particularly on a lot of people’s radars at the moment.
What are your plans for further research into this field?
At the moment I am currently working on a project regarding maternal mortality and morbidity. We’re not specifically looking at obesity. Although we do think similar associations would exist with maternal death, because maternal deaths are even rarer than neonatal deaths it is very difficult to study.
Where can readers find more information?
They can find more information at:-
About Dr. Jenny Cresswell
Dr Jenny Cresswell is an epidemiologist at the MARCH Centre for Maternal, Reproductive & Child Health at LSHTM. She completed her MSc in demography and health in 2007, and was awarded her PhD in 2011 investigating maternal overweight and adverse pregnancy outcomes.
Dr Cresswell is currently working on research projects relating to maternal mortality and morbidity in low-income settings, and on policy changes relating to maternal user fees in West Africa.
Obesity crisis in the U.S. expected to worsen by 2050