Population characteristics
The inclusion criteria for women with CH were met by 650 pregnancies and were classified as group 1 (n=81), group 2 (n=199), group 3 (n=221) and group 4 (n=149). The control group consisted of 142 normotensive women. Maternal and pregnancy characteristics of the four groups of women with CH and the control group are compared in Table 1. In the total cohort of women with CH, compared with controls, maternal age, weight and systolic and diastolic blood pressure at 11-13+6 weeks gestation and the incidence of previous and/or family history of preeclampsia were higher. Approximately 93% of women in groups 3 and 4 were taking one anti-hypertensive medication with 7% taking 2 or more. In groups 3 and 4, compared to group 2, there was a significantly higher weight, systolic blood pressure, incidence of Black racial origin and previous PE. In groups 2 and 3, compared to group 1, systolic and diastolic pressure were lower. Women of group 2 were more likely to be younger and nulliparous when compared to group 3 and with a lower diastolic blood pressure when compared to group 4. Those of group 1 were also more likely to weigh more and be nulliparous when compared to groups 2 and 3, respectively, and with a lower systolic blood pressure compared to group 4. Groups 1 and 2 had a significantly lower rate of preterm PE and higher gestation at delivery when compared to groups 3 and 4 and a significantly lower incidence of SGA neonate with higher birth weight centile when compared to group 3, alone.