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Bariatric and metabolic surgery reduces adverse pregnancy outcomes

Bariatric and metabolic surgery (BMS) can reduce adverse pregnancy outcomes, according to a study that investigated women’s pregnancy status and outcomes as well as the impact of pregnancy intervals after surgery. The researchers recommended that postoperative patients avoid pregnancy until their weight is stable to reduce the risk of adverse pregnancy outcomes. The findings were featured in the paper, ‘A Retrospective Evaluation of Pregnancy Outcomes Following Bariatric Surgery: A Single-Center Experience’, by researchers from The First Affiliated Hospital of Jinan University, Guangzhou, People’s Republic of China.

The authors stated that more than one-third of adults are overweight or live with severe obesity in China, and the overweight and obesity rates of Chinese women of reproductive age are 25.4% and 9.2%, respectively. It is known that obesity can lead to many pregnancy complications and adverse pregnancy outcomes, such as miscarriage, premature delivery, hypertensive disorder complicating pregnancy, gestational diabetes mellitus, foetal abnormalities, postpartum haemorrhage, thrombosis and puerperal infection.


In 2020, there were 12,837 BMS performed in China, but the number of procedures for women of childbearing age is unknown. In addition, such surgery for women of childbearing age also poses clinical challenges for subsequent pregnancies, requiring multidisciplinary collaboration for rigorous prenatal management. Bariatric and metabolic surgery for pregnancy has been reported to reduce the incidence of preeclampsia, gestational diabetes, and large for gestational age infants. However, it may increase the risk of foetal growth restriction, preterm birth, neonatal intensive care unit hospitalisation and increased perinatal mortality.


Some studies have shown that pregnancy after BMS is not associated with adverse perinatal outcomes, other studies have reported significant differences in pregnancy complications and neonatal outcomes between women who conceived within the first 12 months of surgery and those who conceived later. Therefore, the authors noted that the effect of BMS for women’s pregnancy outcomes cannot be fully determined, and they subsequently reviewed the pregnancy and delivery outcomes of women undergoing BMS at their institution to evaluate the impact of BMS on pregnancy.


The study included 31 women of childbearing age who underwent BMS and conceived spontaneously without receiving ovulation stimulation therapy or other medical treatment. All the women had a laparoscopic sleeve gastrectomy and compared with pre-operation, the weight and BMI of the patients after the operation were significantly lower than before, and the mean difference at each observation time point was statistically significant (p<0.05).


For those who delivered after operation (n=18), 9, 7, and 2 gained excessive, adequate, and inadequate weight during gestation, respectively. The BMI at conception was 25.67 (22.44, 31.60) kg/m2, of which 72.2% (n=13) women had a BMI < 30 kg/m2; however, there were three patients had a BMI higher than 35 kg/m2. The weight post-delivery at one year was 70.50 (60.00–87.00) kg. The BMI was 27.17 (23.91, 30.02) kg/m2, of which only 22.2% (n=4) recovered to the original weight (the lowest weight at the time of pregnancy was detected) within one year post delivery, and 77.8% (n=14) still did not recover to the original weight within one year post-delivery (Figure 1).

Figure 1: Changes of body weight and BMI in various periods. (A) Body weight of all patients before and post operation (n = 31); (B) BMI of all patients before and post operation (n = 31); (C) body weight of patients with successful delivery in different periods (n = 18); (D) BMI of patients with successful delivery in different periods (n = 18). *P < 0.05, **P < 0.01, ***P < 0.001.

Seventeen patients had menstrual disorders before surgery, with an overall menstrual disorder rate of 54.84%, while 11 patients had normal menstruation after BMS, with a 64.71% improvement rate. After the operation, the total menstrual disorder rate was 19.35%, significantly lower than before. The difference in menstrual changes before BMS was statistically significant (p=0.000) and three patients with irregular menstruation had polycystic ovary syndrome (PCOS) before BMS and two of them normalised menstrual function postoperatively.


A total of 96.77% of patients undergoing BMS had one or more obesity-related diseases before surgery, including dyslipidaemia, uric acid abnormality, diabetes, sleep apnoea syndrome and hypertension. Most of these comorbidities were resolved after the operation (77.97%) at the follow-up (December 2021). However, two patients with diabetes were still under control with drugs, and two patients with thyroid diseases continued to receive medical treatment. In addition, two patients developed symptoms of anaemia after the operation, and one patient developed dumping syndrome after the operation.

Twenty-two patients had never had a pregnancy before surgery and nine conceived spontaneously. Eighteen cases were successfully delivered, but 12 cases still had a spontaneous abortion, and one patient had induced abortion due to a personal request.


The researchers compared the pregnancy outcomes with pregnancy intervals less than two years (n=10) and ≥2 years (n=20) and found that the abortion rate of pregnant women with pregnancy intervals less than 2 years was higher (p=0.045). Five patients (27.78%) had pregnancy-specific complications, including gestational diabetes mellitus and hypertensive disorder of pregnancy. None of the patients had complications related to delivery. The growth and development of the new-born are normal since the birth follow-up.


In the postoperative successful delivery cohort, they compared the results of pregnancy between ≤24 months after BMS (A1) and >24 months of pregnancy (A2). Among them, 50% (n=9) of patients became pregnant less than 24 months after weight loss, and 50% (n=9) became pregnant more than 24 months after the operation. In group A1, 33.3% underwent LSG, and 66.7% underwent LRYGB. In A2, 55.6% underwent LSG, and 44.4% underwent LRYGB. The study showed no significant difference in pregnancy weight, pregnancy weight gain, late pregnancy weight, postpartum weight, one-year postpartum weight, new-born birth weight, gestational age, delivery mode, and pregnancy complications between the two groups (p>0.05).


They also compared the differences between patients with BMI<30 kg/m2 (B1) and BMI≥30kg/m2 (B2) at conception. In B1, seven (53.8%) patients had LSG and six (46.2%) had LRYGB. In B2, one (20%) had LSG and four (80%) had LRYGB. The study showed differences in weight in the third trimester of pregnancy, weight post-delivery and weight in the first-year post-delivery between the two groups. At the same time, there were no significant differences in weight gain during pregnancy, birth weight of new-born, gestational age, mode of delivery and complications of pregnancy (p>0.05), indicating that BMI increased weight during pregnancy and pregnancy safety were the same at different times of conception


“The present study showed that bariatric and metabolic surgery substantially impact weight control and management in women with obesity and can significantly improve most obesity-related comorbidities,” the researchers concluded. “The abortion rate in pregnancy intervals less than two years was higher than those more than two years. In addition, it is necessary to strengthen the intake of nutrients during postoperative pregnancy. For example, increasing iron supplements can reduce gestational anaemia. Therefore, postoperative trace element supplements and monitoring are also essential.”


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