Hypertension during pregnancy in South Australia, part 1: pregnancy outcomes.

BACKGROUND: There have been conflicting reports about pregnancy outcome in the hypertensive disorders of pregnancy. The present study was undertaken to examine outcomes using a population database. AIMS: To examine for differences in a range of pregnancy outcomes between three different groups of hypertensive women and normotensive women in South Australia. METHODS: Nine pregnancy outcomes were compared for 70,386 singleton pregnancies in the South Australian perinatal data collection in 1998-2001, consisting of 639 women with pre-existing hypertension, 5356 women with pregnancy hypertension, 448 women with superimposed pre-eclampsia and 63 943 normotensive women. Means for the four groups were calculated for birthweight, gestational age, the baby's and mother's length of stay. The groups were also compared for perinatal deaths with an earlier period, 1991-1997. RESULTS: While all three hypertensive groups had high incidences of induction of labour and emergency Caesarean, only pre-existing hypertension and superimposed pre-eclampsia were significantly associated with elective Caesarean section. All hypertensive groups had increased risks for low birthweight and preterm birth and special and neonatal intensive care. Uncomplicated pre-existing hypertension was not associated with small for gestational age infants, but with preterm delivery between 32 and 36 weeks' gestation. Superimposed pre-eclampsia had the worst prognosis for perinatal and maternal morbidity. While pregnancy hypertension held the intermediate position, it was not associated with an increase in perinatal mortality. The perinatal mortality rate for women with hypertensive disorders in 1998-2001 was significantly lower than that of an earlier period and equivalent to that for normotensive women. CONCLUSIONS: Superimposed pre-eclampsia occurs in approximately 40% of pregnancies of women with pre-existing hypertension and has the most severe outcomes. The hypertensive disorders are associated with high levels of morbidity and intervention, but the high perinatal mortality associated with these disorders has fallen significantly.

Hypertension during pregnancy in South Australia, part 2: risk factors for adverse maternal and/or perinatal outcome - results of multivariable analysis.

OBJECTIVE: To identify factors associated with adverse pregnancy outcomes among women with hypertension during pregnancy. DESIGN: A population-based retrospective multivariable analysis using the South Australian perinatal data collection. METHODS: Perinatal data on 70,386 singleton births in 1998-2001 were used in multivariable analyses on three groups: all women combined, all hypertensive women and women with pregnancy hypertension only, in order to identify independent risk factors for requirement for level II/III care, preterm birth, small for gestational age (SGA) birth and maternal length of stay greater than 7 days. RESULTS: The risks for the four morbidities were all increased among women with hypertension compared with normotensive women. Those with pre-existing hypertension had the lowest risk (with odds ratios (OR) 1.26-2.90). Pregnancy hypertension held the intermediate position (OR 1.52-5.70), while superimposed pre-eclampsia was associated with the highest risk (OR 2.00-8.75). Among women with hypertension, Aboriginality, older maternal age, nulliparity and pre-existing or gestational diabetes increased the risk for level II/III nursery care, preterm birth and prolonged hospital stay. Smokers had shorter stays, which may be related to their decreased risk of having a Caesarean section or operative vaginal delivery. Asian women, Aboriginal women, smokers and unemployed women had an increased risk for having an SGA baby, while women with pre-existing or gestational diabetes had a reduced risk. CONCLUSIONS: Among hypertensive pregnant women, nulliparity, older maternal age, Aboriginality, unemployment and diabetes are independent risk factors for one or more major adverse pregnancy outcomes. Smoking does not always worsen the outcome for hypertensive women except for SGA births.

Risk factors for hypertension during pregnancy in South Australia.

OBJECTIVE: To identify risk factors for hypertension in pregnancy among South Australian women. DESIGN: A population-based retrospective analysis using the South Australian perinatal data collection for 1998-2001. METHODS: Three groups of women with hypertension (pre-existing hypertension, pregnancy hypertension, and superimposed pre-eclampsia) were compared with normotensive women using unconditional logistic regression analysis on 70,386 singleton births to identify sociodemographic and clinical risk factors for hypertension in pregnancy. RESULTS: Nulliparity, Aboriginal race and Caucasian race (compared with Asian) and pre-existing and gestational diabetes were demonstrated to be risk factors for all hypertensive disorders, as was increasing maternal age for pre-existing hypertension and superimposed pre-eclampsia. Risk was increased for pregnancy hypertension and superimposed pre-eclampsia among women who gave their occupation as 'home duties' and also for superimposed pre-eclampsia among unemployed women. Women with hypertension were more likely to give birth in teaching hospitals. Urinary tract infections were not found to be a risk factor for any type of hypertension. Smoking during pregnancy was protective for all types of hypertension. CONCLUSIONS: The present study used a statewide population perinatal database and has confirmed that Aboriginal race, Caucasians, nulliparity, and pre-existing and gestational diabetes are independent risk factors for all types of hypertension in pregnancy. Increasing maternal age increased the risk for pre-existing hypertension and superimposed pre-eclampsia. There appeared to be appropriate referral of women with hypertensive disorders to teaching hospitals. A new finding is the increased risk among unemployed women and women engaged in home duties.