Being born small for gestational age increases the risk of severe pre-eclampsia.

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.

SETTING: Sweden.

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.