Association of a woman's own birth weight with her subsequent risk for pregnancy-induced hypertension.

Studies have linked low birth weight to elevated risk for adult hypertension and insulin resistance. However, the relation between birth weight and later risk for pregnancy-induced hypertension (PIH), a disorder associated with insulin resistance and predictive of chronic hypertension, has not been well studied. This case-control study used linked hospital discharge and vital record data from New York State. Subjects were healthy women born in New York State who completed a first pregnancy there between 1994 and 1998. Records from each woman's own birth (1970-1985) were linked to those from her first pregnancy. Cases were 2,180 women diagnosed with PIH. Controls were the 22,955 remaining women with no record of PIH. Birth weight showed a U-shaped relation to risk for PIH, with the highest risks associated with very low and very high birth weights. Relative to women born at 3.5-4.0 kg, odds ratios adjusted for gestational age were 2.1 (95% confidence interval (CI): 1.1, 3.9) and 1.6 (95% CI: 1.1, 2.4), respectively, for women with birth weights less than 1.5 kg and greater than 4.5 kg. Adjustment for other perinatal factors reduced the association with high birth weight to 1.1 (95% CI: 0.7, 1.7) but strengthened that with lower birth weights, leaving a strong, inverse relation between birth weight and PIH risk (p for trend < 0.0001). These findings support a possible role for early life factors, particularly fetal growth, in the etiology of PIH.