Effect of Obesity, Diabetes and Bariatric Surgery on Pregnancy Outcomes

The obesity epidemic is growing worldwide and in the UK this is perpetuated with a third of women classified as overweight/obese in 2020. Many of these woman are of childbearing age and go on to have high risk pregnancies which are often complicated by gestational or pre-existing (type 2 diabetes mellitus (GDM, T2DM). Bariatric surgery is the most successful treatment of sustainable weight loss and is associated with a reduction in rates of GDM, pre-eclampsia, delivery of large babies but increased risk of delivery of small babies and preterm delivery.

The aims of the study are to investigate the maternal and fetal/neonatal, biophysical and biochemical, intra-uterine environment and postnatal profile of pregnancies:

1. affected by maternal obesity and/or GDM/T2DM compared to pregnancies with normal maternal body mass index (BMI).
2. with previous maternal bariatric surgery compared to pregnancies without previous bariatric surgery but matched for maternal pre-surgery and early pregnancy BMI.

This is an observational study. The investigators are planning to study pregnant women with normal BMI or overweight (BMI\<30), obesity (BMI ≥30) and glucose disorders (GDM and T2DM). The investigators will also study pregnant women with previous bariatric surgery (gastric band, sleeve gastrectomy or gastric bypass) and compare them with pregnant women of similar pre-surgery and early pregnancy BMI, but no hisotry of weight loss surgery.

For all the participants and serially during pregnancy (at 12-14, 20-24, 26-28, 30-32, 35-37 weeks gestation and postnatally (at 6 weeks, 3 months, 12-24 months and 3-7 years of age), the investigators will perform the following investigations:

Maternal investigations: Demographics and medical history will be recorded, weight, height, waist to hip ratio and blood pressure will be measured, blood, urine, stool samples and vaginal swabs will be obtained, cervical length (by trans-vaginal ultrasound) will be measured and maternal echocardiography will be performed. Maternal glucose homeostasis will be assessed at 26-28 weeks of gestation, by a full oral glucose tolerance test, HOMA, home glucose monitoring and/ or continuous glucose monitoring (CGM), depending on the group the women belong to.

Fetal investigations: Fetal growth and well being will be assessed by 2D, 3D and Doppler ultrasound, fetal echocardiography will be performed.

At and following delivery: Maternal blood and urine samples and subcutaneous and omental fat (if Caesarean section is performed) will be obtained, placental tissue will be stored. Neonatal cord blood will be obtained, birthweight (percentiles), anthropometric characteristics will be measured, meconium and urine samples will be obtained and neonatal MRI (to assess body fat distribution) will be arranged.

Postnatal follow up visits for the mother and the infant (at 6 weeks, 3 months, 12-24 months, 3-7 years old) will be arranged and maternal and infant blood and urine samples will be requested and obtained.

Eligibility Criteria:
Inclusion Criteria:

* Pregnant women with normal size (BMI \<30)
* Pregnant women with obesity (BMI ≥30)
* Pregnant women with glucose disorders
* Pregnant women with previous bariatric surgery

Exclusion Criteria:

* Pregnant women less than 18 years of age
* Pregnant women with twins/triplets