Bariatric surgery to treat obesity is increasing in frequency, doubling between 2005 and 2015. In 2014-15, 79% of the 22,700 hospital separations for bariatric surgery in Australia were performed on women, particularly in women of child bearing age. [1]Gastric sleeve (68%) and gastric band (19%) outnumber the gastric bypass (roux en y or biliopancreatic diversion surgeries) (10%) [1]. Pregnancy following bariatric surgery is associated with lower rates of hypertensive disorders but higher rates of small for gestational age infants and pre term delivery [2]. This data-linkage project aims to analyse the outcomes of Queensland pregnancies and neonatal outcomes in women following bariatric surgery between 2013-2018 and matched controls.
The Queensland Hospital Admitted Patient Data Collection (QHAPDC) contains statewide data capturing information from all hospitals permitted to admit patients. The statewide Perinatal Data Collection collects information on all births in Queensland. Recorded data include maternal demographics, obstetric history, antenatal care, labour and delivery details, neonatal outcomes and postnatal details. In total, 2,018 births in 1,677 women were registered in the statewide perinatal dataset with evidence of prior maternal bariatric surgery via QHAPDC between 2013-2018. The first pregnancy following bariatric surgery for each woman was used for analysis. Of these 1,351 singleton births were matched on BMI, smoking, age and parity to 13,510 controls using a matching ratio of 1 case to 10 controls.
Matching was effective. There was no difference between case and control women for age category, parity, smoking or BMI, p=1.00, p=0.24, p=0.97 and p=0.82 respectively. Assisted reproductive technology use was different with 11.2% (n=151) women with previous bariatric surgery requiring assisted conception compared to 8.2% (n=1,109) control women (p<0.001). Women were aged between 25-29 years in 25.7% (n=3,817), 30-34 years in 34.5% (n=5,138) and 35-39 years in 23.9% (n=3,553). Less than a tenth of women were less than 20 or greater than 40 years of age. Gestational age at delivery and infant birthweight were different between women who had undergone previous bariatric surgery and controls with a median age of 38 weeks vs 39 weeks (p<0.001) and a mean birthweight of 3219 grams vs 3415 grams (p<0.001).
Initial findings indicate that women with previous bariatric surgery have higher rates of assisted conception and earlier delivery compared to matched controls. Ongoing analysis including multivariable regression models will be performed.