Interpretation
Compared to studies reported globally our incidence was a little higher.
This is probably due to the inclusion of only high-risk pregnant women
in our study, whereas in other studies the comparison was made with
normotensive pregnant women. Prediction and Prevention of Preeclampsia
and Intrauterine Growth Restriction (PREDO) Project, a study conducted
among 972 pregnant women in the Finnish population with risk factors for
PE reported the incidence of PE among women with previous preeclamptic
pregnancy and BMI of >30kg/m2was 28.6%,
and among the pregnant women with chronic hypertension and one or more
risk factors, the incidence was 24.6%8. A US-based
study conducted among the high-risk cohort of pregnant women who
received skilled home nursing, reported an incidence of 26.9%9. Out of various factors we studied, the absence of a
family history of chronic hypertension, history of abortion,
non-consanguineous marriage and maternal blood group being AB-type were
reported as significant protective factor and sex of the new-born being
female was found to be the risk factor for PE. The possible reason for
the development of PE in 67/174 high-risk pregnant women is mainly due
to five major factors like a family history of chronic high blood
pressure, absence ofa history of abortion, consanguineous marriage,
maternal blood group other than ‘AB’ and sex of the new-born.
History of abortion was found to be a protective factor in this study.
No studies reported among the high-risk group, but within the pregnant
women, various studies reported that prior abortion as a protective
factor from developing PE10,11. Analogous to our
findings, previous studies have reported the protective effect of both
induced10–14 and spontaneous
abortions12,15,16. The reason is unclear. But the
decreased risk of PE in women with a history of abortion might be due to
the longer periods of sexual cohabitation17, thereby
the protective factors like transforming growth factor β (TGF-β) present
in the seminal plasma might have caused the immune-deviating effects
that enhanced the foetal/placental development which further decreased
the risk of PE18–22. In contrast to our findings,
Trogstad et al. reported an increased risk of PE in women with a history
of spontaneous abortions13. This might be due to the
association of spontaneous abortions with infertility, which is the
potential independent risk factor for PE23.Our finding
of the absence ofa family history of chronic hypertension as a
protective factor from developing PE is supported by a Brazilian
study24. Another study proved that the frequency of PE
is greater in women who had hypertension for at least four years and
also in those with PE during a previous pregnancy25.
The culture of marrying within the blood relations is more prevalent in
south India26and women in consanguineous unions are
more likely to have adverse pregnancy outcomes including stillbirth and
abortion27,28.Consanguineous marriages continue to be
a critical predictor of adverse pregnancy outcomes in
India29. Out of many studies attempted to find the
association between PE and consanguinity30–32, only a
few studies reported an increased risk of PE in marriages with
biological relatives33.Though the exact reason is not
clear, consanguinity could allow more chance for homozygosity for the
same single recessive gene for mother and foetus and consequently more
chance for PE.
An important finding of the current study is the protective relation
between blood group AB (non-O) and PE. Our finding contradicts a
population-based nested case-control study that demonstrated AB blood
group as a risk factor forPE34 and a large Swedish
cohort study that showed blood group O as a protective factor against
PE35. Similar to our findings, Amin et al reported
blood group O as a risk factor36 and a contradictory
finding by Francine et al., reported non-O blood groups as risk factors
while blood group O is protective against PE37.