Objective
Preeclampsia is among the three leading causes of maternal mortality and morbidity
worldwide, occurs in 6-8% of all pregnancies, and is estimated to account for at least nine
percent of maternal deaths in Africa. Studies from developed countries show that high
prepregnancy BMI increases the risk of preeclampsia. We examined the association of
prepregnancy body mass index and changes of prepregnancy body weight between
pregnancies with risk of preeclampsia in the second pregnancy. In the term preeclampsia we
also include cases of eclampsia.
Method
A historic registry based study was used, analysing births registered in the Kilimanjaro
Christian Medical Center (KCMC) birth registry between July 2000 and May 2013. Two sets
of data were analysed; singleton births of gravida 1 or 2 mothers (n= 17, 750 births), and the
linked first two recorded singleton births to a woman, irrespective of gravidity (n =3, 595
mothers). Prepregnancy BMI was categorized according to WHO categories underweight
(less than 18.5), normal (18.5 – 24.9), overweight (25.0 – 29.9) and obese (30 or greater).
Measured confounders were adjusted for in multivariable models.
Results
Among the 17,750 singleton births, 9.1 % of the mothers were underweight, 24.0 % were
overweight, and 7.4 % were obese. Five hundred and eighty-two pregnancies (3.3 %) were
affected by preeclampsia. Compared to women of normal BMI, overweight and obese women
had an increased risk of preeclampsia (AOR 1.5 (95%CI 1.2 – 1.7 and, 1.7(1.2 – 2.1),
respectively, while underweight was protective (AOR 0.8 (0.8 - 1.1). Among 3,595 mothers
without preeclampsia in their first recorded pregnancy, incidence of preeclampsia was 2% in
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the second recorded pregnancy. Weight loss, but not weight gain between the pregnancies was
associated with risk of preeclampsia in the last pregnancy. The effect of weight change did
not change after adjustment for BMI in second pregnancy.
Conclusion
The association between prepregnancy body mass index and preeclampsia in this population
of pregnant women in Northern Tanzania corresponds with earlier findings from developed
countries. Overweight and obesity should be considered an obstetric risk factor is this
population.