Pregnancy-induced hypertension in women who were born small.

We assessed whether a pregnant woman who was born small for gestational age has increased risk of pregnancy-induced hypertension (PIH), and whether the same applies to a pregnant partner of a man who was born small for gestational age. We linked generational data from the medical birth registry of Norway (1967-2005). Female and male newborns were identified as parents with 197,716 and 131,959 first or second pregnancies from 1998 to 2005, respectively. In the first pregnancy in women who were born with birth weight <2.5, 2.5 to 4.9, and 5 to 9.9 birth weight percentiles, odds ratios of PIH in general adjusted for smoking and maternal age were 1.5, 1.4, and 1.1, respectively, compared with percentile 25 to 75. In the second pregnancy, corresponding odds ratios were 1.5, 1.3, and 1.2, respectively. A similar trend was found in all of the subgroups of PIH. Women who were born below the 5th birth weight percentile were 2 to 3 times more likely to have preeclampsia with onset before 34 weeks of gestation than those with birth weight between the 25th and 75th percentiles (adjusted odds ratios: 1.8 to 2.8). Father's birth weight for gestational age was not associated with mother's development of PIH. In conclusion, women who were born growth restricted after normotensive pregnancies were more likely to develop PIH later in life. The lack of association with the father's size at birth agrees with the hypothesis of fetal environmental origin of PIH, although maternal genetic transmission of susceptibility for PIH cannot be ruled out.