Study population
All pregnant women who stayed at least 6 months in the region and attended antenatal care follow-up and/or delivery during the study period at any of the public health facilities of Bahir Dar City and who met the inclusion criteria comprised the study population.
Cases were pregnant women diagnosed to have any form of pre-eclampsia/eclampsia during ANC follow-up or delivery care by an obstetrician. Pre-eclampsia was diagnosed after 20 weeks of pregnancy if they had a blood pressure of ≥140/90 mmHg measured at least twice at 4- h intervals and protein in their urine confirmed by a laboratory test.
Controls were normotensive women delivered in the same health facilities at the same time as cases were enrolled. The highest proportion (90%) of pre-eclampsia occurs from 34 weeks of gestation to delivery, 5% from 20 to 34 weeks and the remaining 5% from delivery to 48 h post partum. Therefore, a woman who did not have the disease initially may end up with pre-eclampsia unless proven otherwise. Hence, to avoid misclassification of potential cases as controls, we waited to see the outcome of all the controls until 48 h post partum.