OBJECTIVE:To examine the maternal and foetal risks of adverse pregnancy outcome in relation to maternal obesity, expressed as body mass index (BMI, kg=m 2 ) in a large unselected geographical population. DESIGN: Retrospective analysis of data from a validated maternity database system which includes all but one of the maternity units in the North West Thames Region. A comparison of pregnancy outcomes was made on the basis of maternal BMI at booking. SUBJECTS: A total of 287 213 completed singleton pregnancies were studied including 176 923 (61.6%) normal weight (BMI 20 -24.9), 79 014 (27.5%) moderately obese ) and 31 276 (10.9%) very obese (BMI ! 30) women. MEASUREMENTS: Ante-natal complications, intervention in labour, maternal morbidity and neonatal outcome were examined and data presented as raw frequencies and adjusted odds ratios with 99% confidence intervals following logistic regression analysis to account for confounding variables. RESULTS: Compared to women with normal BMI, the following outcomes were significantly more common in obese pregnant women (odds ratio (99% confidence interval) for BMI 25 -30 and BMI ! 30 respectively): gestational diabetes mellitus (1.68 (1.53 -1.84), 3.6 (3.25 -3.98)); proteinuric pre-eclampsia (1.44 (1.28 -1.62), 2.14 (1.85 -2.47)); induction of labour (2.14 (1.85 -2.47), 1.70 (1.64 -1.76)); delivery by emergency caesarian section (1.30 (1.25 -1.34), 1.83 (1.74 -1.93)); postpartum haemorrhage (1.16 (1.12 -1.21), 1.39 (1.32 -1.46)); genital tract infection (1.24 (1.09 -1.41), 1.30 (1.07 -1.56)); urinary tract infection (1.17 (1.04 -1.33), 1.39 (1.18 -1.63)); wound infection (1.27 (1.09 -1.48), 2.24 (1.91 -2.64)); birthweight above the 90th centile (1.57 (1.50 -1.64), 2.36 (2.23 -2.50)), and intrauterine death (1.10 (0.94 -1.28), 1.40 (1.14 -1.71)). However, delivery before 32 weeks' gestation (0.73 (0.65 -0.82), 0.81 (0.69 -0.95)) and breastfeeding at discharge (0.86 (0.84 -0.88), 0.58 (0.56 -0.60)) were significantly less likely in the overweight groups. In all cases, increasing maternal BMI was associated with increased magnitude of risk. CONCLUSION: Maternal obesity carries significant risks for the mother and foetus. The risk increases with the degree of obesity and persists after accounting for other confounding demographic factors. The basis of many of the complications is likely to be related to the altered metabolic state associated with morbid obesity.

The obstetric risks of adverse outcome during pregnancy in women aged > or =35 years were quantified using a retrospective analysis of data from 385 120 singleton pregnancies in the North West Thames Region, UK, between 1988 and 1997. A comparison of pregnancy outcome was made on the basis of maternal age at delivery: 18-34 years (n = 336 462), 35-40 years (n = 41 327) and women aged > 40 years (n = 7331). Women aged <18 years (n = 5246) were excluded from the study. Data are presented as percentages of 18-34 year old women, 35-40 year old and > 40 year old women, with adjusted odds ratios (OR) according to age group. Pregnant women aged 35-40 years were at increased risk of: gestational diabetes, OR = 2.63 [99% confidence interval (CI) 2.40-2.89]; placenta praevia = 1.93 (1.58-2.35); breech presentation = 1.37 (1.28-1.47); operative vaginal delivery = 1.5 (1.43-1.57); elective Caesarean section = 1.77 (1.68-1.87); emergency Caesarean section = 1.59 (1.52-1.67); postpartum haemorrhage = 1.14 (1.09-1.19); delivery before 32 weeks gestation = 1.41 (1.24-1.61); birthweight below the 5th centile = 1.28 (1.20-1. 36); and stillbirth = 1.41 (1.17-1.70). Women aged >40 years had higher OR for the same risks. Pregnant women aged >/=35 years are at increased risk of complications in pregnancy compared with younger women.

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Background: Our aim was to identify and compare modifiable risk factors associated with adverse pregnancy outcomes in women with type 1 and type 2 diabetes and to identify effective maternity clinics. Methods:We included 17,375 pregnancies in 15,290 women with diabetes in a populationbased cohort study across 172 maternity clinics in England, Wales and the Isle of Man.Obstetric complications (preterm delivery, large birthweight) and adverse pregnancy outcomes (congenital anomaly, stillbirth, neonatal death) were obtained for pregnancies completed between 01 January 2014 and 31 December 2018. We assessed associations between modifiable (glycaemia, obesity, clinic) and non-modifiable risk factors (age, deprivation, ethnicity) with pregnancy outcomes.Results: Of 17,375 pregnancies, 8,690 (50.0%) were in women with type 1 and 8,685 (50.0%) in women with type 2 diabetes. The rates of preterm delivery (42.5% type 1, 23.4% type 2), and large birthweight (52.2% type 1, 26.2% type 2) were higher in type 1 diabetes (p<0.001).The prevalence of congenital anomaly (44.8/1000 type 1, 40.5/1000 type 2; p=0.175), and stillbirth (10.4/1000 type 1, 13.5/1000 type 2; p=0.072) did not differ but neonatal death rates (7.4/1000 type 1, 11.2/1000 type 2; p=0.013) were higher in type 2 diabetes. Independent risk factors for perinatal death were third trimester HbA1c > 48mmol/mol (OR 3.06, 95% CI 2.16 to 4.33), living in the highest deprivation quintile (OR 2.29 95% CI 1.16 to 4.52) and having type 2 diabetes (OR 1.65 95% CI 1.18 to 2.31). Variations in glycaemia and large birthweight were associated with maternal characteristics (diabetes duration, deprivation, BMI) without substantial differences between clinics.Interpretation: Our data highlight persistent adverse pregnancy outcomes in type 1 and type 2 diabetes. Maternal glycaemia and obesity are the key modifiable risk factors. No clinics were achieving appreciably better outcomes, suggesting that healthcare system changes are needed

Pregnant women less than 18 years old were more likely to deliver preterm than older women. In most other respects they have less maternal and perinatal morbidity and were more likely to have normal vaginal deliveries.