Objective The first aim of this study was to investigate the risk of pre-eclampsia, both mild and severe, in women born small for gestational age (SGA). The second aim was to investigate whether the risk is modified by pre-eclampsia in the previous generation.
Design Population-based cohort study.
Population A population of 118 634 women registered both as newborns and as mothers in the Swedish Medical Birth Register of 1973–2003. Of these, 6883 had been born SGA. Only primiparas and singletons were included.
Methods The pregnancies that the women were born out of were analysed with regard to presence of pre-eclampsia, while their own pregnancies were analysed regarding age at delivery, smoking, body mass index and incidence of mild or severe pre-eclampsia. Multiple logistic regression analysis was used. In a first step, we adjusted for maternal characteristics, and in a second step, for pre-eclampsia in the previous generation.
Main outcome measures Odds ratio for mild and severe pre-eclampsia.
Results In women born SGA, the adjusted odds ratio (first step) for mild pre-eclampsia was 1.19 (95% CI 1.03–1.38), while for severe pre-eclampsia it was 1.69 (95% CI 1.40–2.02) compared with those not born SGA. After the second-step adjustment, the odds ratio for mild pre-eclampsia was 1.16 (95% CI 1.00–1.35) and for severe pre-eclampsia was 1.62 (95% CI 1.35–1.95). No statistically significant effect modification from pre-eclampsia in the previous generation was shown.
Conclusions Women born SGA suffer a markedly increased risk of severe pre-eclampsia. Exposure to pre-eclampsia during a woman’s own fetal development significantly increases her risk of pre-eclampsia but does not modify the SGA effect.