Smoking in Dutch pregnant women and birth weight.

In this study 796 ambulatory singular pregnant women were questioned about their smoking habits both before and during pregnancy (ambispective). Important covariates such as parity, blood pressure, maternal weight gain, salt- and alcohol consumption and length of gestation were taken into account. At the beginning of pregnancy 52% of the questioned women smoked; 36% smoked in the seventh/eighth month of pregnancy. A dose-response relationship was found between the number of cigarettes smoked per day and birth weight. For those pregnant women who still smoked after 7 months of pregnancy an average birth weight loss of 24 g was found per cigarette per day. Even after controlling for covariates, there still remains an independent influence of smoking on birth weight loss on the average of 19 g for each cigarette smoked per day.

Cesarean section and maternal age in low-risk nulliparas.

The relationship between maternal age and cesarean section in low-risk nulliparas was analysed in 7454 perinatal clinical records selected from eleven databases of Latin American institutions obtained with a comprehensive perinatal information system. The risk of cesarean section in nulliparas between 29 and 49 years of age was found to be three times higher than that corresponding to pregnant women of lesser age. This clearly more aggressive obstetrical conduct could not be explained by the main indications for cesarean section.

Haematologic parameters and pregnancy outcome. A prospective cohort study in the third trimester.

The relationship between haematologic parameters and pregnancy outcome was investigated in a prospective study, taking important covariates into consideration. A questionnaire asking information about smoking, alcohol consumption and iron intake was completed by a consecutive series of 796 ambulatory singleton pregnant women at 31-32 weeks of gestation. Subsequently, haematologic parameters were measured. After delivery, birth weight, gestation length and blood pressure values during pregnancy were abstracted from the obstetricians' records. Low birth weight (less than 2.500 g) and preterm birth (less than 37 weeks), were significantly more frequently seen in women with high haemoglobin (greater than or equal to 8.0 mmol/l) or high haematocrit (greater than 38%) values, with Mantel-Haenszel odds ratios varying from 2.4 to 4.2. Also a high erythrocyte count (greater than or equal to 4.5/pl) was correlated with low birth weight, while for mean corpuscular volume (MCV) no such relationships were found. Pregnancy induced hypertension was positively associated with haemoglobin, haematocrit and erythrocyte count, but could not fully explain the relationships between these parameters and adverse outcomes. Using multiple logistic regression with low birth weight and or preterm birth as the dependent variable, the effect of haematocrit still was demonstrable after controlling for smoking, hypertension, parity, alcohol consumption and iron intake. These results are in agreement with the hypothesis that a higher blood viscosity is a risk factor for suboptimal placenta-perfusion.