Non-elective caesarean delivery due to ineffective uterine contractility or due to obstructed labour in relation to maternal body mass index.

OBJECTIVE: To assess whether non-elective caesarean section due to obstructed labour and/or ineffective uterine contractility was associated with maternal body mass index (BMI). STUDY DESIGN: The prospective dataset from the Swedish Medical Birth Registry consisted of 233,887 nulliparous women with a spontaneous onset of labour categorized in six classes of pre-pregnancy BMI, who delivered in Sweden between, January 1, 1999 and December 31, 2005. The mode of delivery was classified as either vaginal or by caesarean section. The caesarean section was classified as either elective or non-elective. Adjusted risks for non-elective caesarean section due to ineffective uterine contractility, or obstructed labour or fetal distress were determined using Mantel-Haenszel technique. RESULTS: The risk of a non-elective caesarean section due to obstructed labour was not significantly associated with maternal BMI. However, ineffective uterine contractility was significantly associated with maternal BMI and the risk of non-elective caesarean delivery due to labour arrest disorders increased with increasing BMI, reaching a 4-fold increased risk among the morbidly obese women. The risk of non-elective caesarean section due to fetal distress also increased significantly with increasing maternal BMI. CONCLUSIONS: It appears that ineffective labour could be a factor leading to the increased risk of non-elective caesarean section among obese and morbidly obese women. These findings challenge obstetricians to learn more about how to manage oxytocin infusions during labour in relation to maternal BMI.

Optimal gestational weight gain for body mass index categories.

OBJECTIVE: To establish optimal gestational weight gain for each maternal body mass index (BMI) category based on significant risk estimates of adverse maternal and fetal outcome. METHODS: The study population consisted of 298,648 singleton pregnancies delivered in Sweden between January 1, 1994, and December 31, 2004. The number of individuals in each weight gain class was compared with the number of individuals in all other weight gain classes in the same BMI group with regard to adverse maternal and fetal outcome. Odds ratios were calculated after suitable adjustments. RESULTS: The optimal gestational weight gain in women by prepregnancy BMI was 9-22 lb (4-10 kg) for BMI less than 20; 5-22 lb (2-10 kg) for BMI 20-24.9; less than 20 lb (less than 9 kg) for BMI 25-29.9; and less than 13 lb (less than 6 kg) for BMI of 30 or more. CONCLUSION: The gestational weight gain limits for BMI categories determined in this large population-based cohort study from Swedish Medical Registers showed that a decreased risk of adverse obstetric and neonatal outcomes was associated with lower gestational weight gain limits than was earlier recommended, especially among obese women.

Obstetric outcome of 6346 pregnancies with infants affected by congenital heart defects.

OBJECTIVE: To evaluate whether pregnancies with infants affected by congenital heart defects are associated with adverse obstetric and perinatal outcome. STUDY DESIGN: In a prospective population-based cohort study from Sweden (1992-2001), 6346 singleton pregnancies with infants affected by congenital heart defects were, after suitable adjustments, compared to all delivered women. RESULTS: The prevalence of cardiovascular defects was 9.1 per 1000 births. Among them, mothers of 6346 infants (71%) had information on maternal smoking habits and maternal height and weight in early pregnancy that enabled the calculation of BMI. All cases with known chromosomal abnormalities and/or maternal pre-existing diabetes were excluded. Eighty-four percent (n=5338) had an isolated cardiovascular defect. Severe types occurred in 21.7% (n=1378). In the group of pregnancies with infants affected by congenital heart defects as compared to all delivered women, there was an increased risk of the following outcomes (adjusted OR (95%CI)): pre-eclampsia (1.21 (1.06-1.37)), cesarean section (1.91 (1.79-2.03)), instrumental delivery (1.21 (1.10-1.34)), pre-term delivery (2.58 (2.39-2.79)), small-for gestational age (1.96 (1.77-2.16)), meconium aspiration (1.51 (1.28-1.77)), and fetal distress (1.38 (1.17-1.63)). CONCLUSIONS: Pregnancies with infants affected by congenital heart defects are associated with several obstetric and neonatal complications.

Maternal morbid obesity and the risk of adverse pregnancy outcome.

OBJECTIVE: To evaluate whether morbidly obese women have an increased risk of pregnancy complications and adverse perinatal outcomes. METHODS: In a prospective population-based cohort study, 3,480 women with morbid obesity, defined as a body mass index (BMI) more than 40, and 12,698 women with a BMI between 35.1 and 40 were compared with normal-weight women (BMI 19.8-26). The perinatal outcome of singletons born to women without insulin-dependent diabetes mellitus was evaluated after suitable adjustments. RESULTS: In the group of morbidly obese mothers (BMI greater than 40) as compared with the normal-weight mothers, there was an increased risk of the following outcomes (adjusted odds ratio; 95% confidence interval): preeclampsia (4.82; 4.04, 5.74), antepartum stillbirth (2.79; 1.94, 4.02), cesarean delivery (2.69; 2.49, 2.90), instrumental delivery (1.34; 1.16, 1.56), shoulder dystocia (3.14; 1.86, 5.31), meconium aspiration (2.85; 1.60, 5.07), fetal distress (2.52; 2.12, 2.99), early neonatal death (3.41; 2.07, 5.63), and large-for-gestational age (3.82; 3.50, 4.16). The associations were similar for women with BMIs between 35.1 and 40 but to a lesser degree. CONCLUSION: Maternal morbid obesity in early pregnancy is strongly associated with a number of pregnancy complications and perinatal conditions. LEVEL OF EVIDENCE: II-2

Maternal obesity and infant heart defects.

OBJECTIVE: This study determined whether obese women have an increased risk of cardiovascular defects in their offspring compared with average weight women. RESEARCH METHODS AND PROCEDURES: In a case-control study, prospectively collected information was obtained from Swedish medical health registers. The study included 6,801 women who had infants with a cardiovascular defect and, as controls, all delivered women (N = 812,457) during the study period (1992 to 2001). Infants with chromosomal anomalies or whose mothers had pre-existing diabetes were excluded. Obesity was defined as BMI >29 kg/m(2), and morbid obesity was defined as BMI >35 kg/m(2). Comparisons were made with average weight women (BMI = 19.8 to 26 kg/m(2)). RESULTS: In the group of obese mothers, there was an increased risk for cardiovascular defects compared with the average weight mothers [adjusted odds ratio (OR) = 1.18; 95% CI, 1.09 to 1.27], which was slightly more pronounced for the severe types of cardiovascular defects (adjusted OR = 1.23; 95% CI, 1.05 to 1.44). With morbid obesity, the OR for cardiovascular defects was 1.40 (95% CI, 1.22 to 1.64), and for severe cardiovascular defects, the OR was 1.69 (95% CI, 1.27 to 2.26). There was an increased risk for all specific defects studied among the obese women, but only ventricular septal defects and atrial septal defects reached statistical significance. DISCUSSION: In this sample, a positive association was found between maternal obesity in early pregnancy and congenital heart defects in the offspring. A suggested explanation is undetected type 2 diabetes in early pregnancy, but other explanations may exist.

Chlorination byproducts and nitrate in drinking water and risk for congenital cardiac defects.

Drinking water disinfection byproducts have been associated with an increased risk for congenital defects including cardiac defects. Using Swedish health registers linked to information on municipal drinking water composition, individual data on drinking water characteristics were obtained for 58,669 women. Among the infants born, 753 had a cardiac defect. The risk for a cardiac defect was determined for ground water versus surface water, for different chlorination procedures, and for trihalomethane and nitrate concentrations. Ground water was associated with an increased risk for cardiac defect when crude rates were analyzed but after suitable adjustments this excess rate was found to be determined by chlorination procedures including chlorine dioxide. Chlorine dioxide appears itself as an independent risk factor for cardiac defects (adjusted odds ratio 1.61 (95%CI 1.00-2.59)). The risk for cardiac defects increased with increasing trihalomethane concentrations (P=0.0005). There was an indicated but statistically nonsignificant excess risk associated with nitrate concentration. The individual risk for congenital cardiac defect caused by chlorine dioxide and trihalomethanes is small but as a large population is exposed to public drinking water, the attributable risk for cardiac defects may not be negligible.

Risk factors for cardiovascular malformation--a study based on prospectively collected data.

OBJECTIVES: The aim of this study was to identify risk factors for cardiovascular malformation. METHODS: In a case-referent study prospectively collected data were obtained from original medical records. The study included 277 woman who had infants with a severe cardiac defect, and for each case two referents (medical records study) were included. Data on parental age, maternal reproductive history, disease in early pregnancy, reported maternal use of drugs and alcohol, smoking habits, parental occupation, and maternal body mass index (BMI) were extracted. When data were available from Swedish medical health registers, a comparison was made (register study) between all infants with cardiovascular defects (2208) and all infants born (175 768). RESULTS: Maternal diabetes mellitus was associated with an increased risk for cardiovascular malformation [odds ratio (OR) 2.38, 95% confidence interval (95% CI) 1.36-4.15], as was a high BMI (> 29) (OR 1.46, 95%CI 1.12-1.90). A tendency towards an increased risk was found for involuntary childlessness, spontaneous abortion, thyroid drugs, and nonsteroid anti-inflammatory drugs. CONCLUSIONS: Some known risk factors for cardiac defects (eg, maternal diabetes mellitus and the use of antiepileptics) could be identified. Other postulated risk factors could not be verified, for example, paternal age and parental occupation. The use of medicinal drugs seems not to be a major factor in the etiology of cardiac defects. It is possible, however, that there is an association with the use of nonsteroid anti-inflammatory drugs or drugs for thyroid disease. The relationship between a high BMI and cardiovascular malformation observed in this study may be explained by impaired maternal glucose tolerance.