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Bariatric surgery in women of childbearing age

A. Alatishe, B.J. Ammori, J.P. New, A.A. Syed
DOI: http://dx.doi.org/10.1093/qjmed/hct081 717-720 First published online: 10 April 2013


Background: Although bariatric surgery in women of childbearing age reduces the risks of pregnancy complications associated with maternal obesity, little is known of the effect of gestation on weight loss outcomes.

Aim: To study weight loss and pregnancy outcomes after bariatric surgery in women of childbearing age.

Design and Methods: We performed a retrospective, observational cohort analysis of women aged 18–45 years in a university teaching hospital. The results shown represent mean ± standard deviation where appropriate.

Results: A total of 232 women aged 34.0 ± 5.9 years with pre-operative weight 137.7 ± 21.3 kg and body mass index (BMI) 50.6 ± 7.2 kg/m2 underwent bariatric surgery that included 197 (84.9%) gastric bypass, 19 (8.2%) gastric banding, 8 (3.4%) sleeve gastrectomy and 8 other procedures. Twenty-one women had 28 pregnancies following bariatric surgery, of which 24 (85.7%) resulted in live births, 3 (10.7%) terminations of pregnancy and 1 (3.6%) spontaneous miscarriage. The pregnancy group was younger compared with the non-pregnancy group (28.0 ± 5.4 vs. 34.6 ± 5.6 years; P < 0.001) but well matched for pre-operative weight (136.5 ± 18.5 vs. 137.8 ± 21.6 kg), BMI (49.2 ± 7.4 vs. 50.7 ± 7.2 kg/m2) and bariatric procedure. The interval between bariatric surgery and first pregnancy was a median 11 months. The pregnancy group lost 70.4% of excess weight compared with 70.0% in the non-pregnancy group at median 30 months of follow-up.

Conclusion: Pregnancy after bariatric surgery is safe and does not adversely affect weight loss outcomes.


Maternal obesity, defined as a body mass index (BMI) ≥30 kg/m2 during pregnancy, increases the risk of various pregnancy complications such as miscarriage, foetal abnormality, prematurity, macrosomia, dystocia, birth injury, still birth and neonatal death, pregnancy-induced hypertension, gestational diabetes, thrombosis, difficulty in delivery leading to higher caesarean rates, anaesthetic complications, infection, post-partum haemorrhage and maternal mortality.1–4 Annual data from the Health Survey for England show a worrying increase in the prevalence of clinical obesity (BMI ≥ 30 kg/m2) in women aged 16–44 years from 12.4% at the first survey in 1993 to 20.2% at the latest in 2010.5 Furthermore, the Confidential Enquiry into Maternal and Child Health reported that 5% of pregnant women had a BMI ≥35 kg/m2 (Class II and Class III obesity) at any point in pregnancy, translating into ∼38 478 maternities each year in the UK.2 It is to be noted in this context that the use of bariatric surgery for the correction of morbid obesity has increased exponentially during the past decade,6 particularly among women of reproductive age, and rates of many adverse maternal and neonatal outcomes are significantly lower in women who become pregnant following bariatric surgery.3,7,8 Women are generally advised to avoid pregnancy for 12–18 months after bariatric surgery due to fears of foetal under-nutrition and reduced weight loss benefits.1,3 However, little is known of the effect of gestation following bariatric surgery on maternal weight loss outcomes.


We carried out a retrospective, observational cohort analysis of bariatric surgical patients in the setting of a National Health Service university teaching hospital that serves the population of Greater Manchester in northwest England.9,10 We included all women of childbearing age (18–45 years) who had undergone bariatric surgery between January 2005 and April 2011. Baseline and post-operative data at a median 2, 6, 10, 15, 21 and 30 months were extracted. We reported weight loss outcomes as percentage excess weight loss (%EWL), where excess weight was the difference of the current weight and the ideal weight of the individual, assuming a BMI of 25 kg/m2.11 The %EWL was computed by the formula [Initial weight (kg) − Current weight (kg)]/[Initial weight (kg) − Ideal weight (kg)] × 100, where Ideal weight (kg) = 25 × [Height (m)]2. We reported descriptive statistics with measures of dispersion as appropriate. Comparisons between paired measurements were performed by Student paired-samples t-test. Comparisons among groups were done by one-way analysis of variance followed by Tukey’s multiple comparison test. Fisher’s exact test was used to analyse contingency tables of categorical variables. P < 0.05 was considered statistically significant and 95% confidence interval (95% CI) was reported as a measure of precision. Data were analysed with Statistical Package for the Social Sciences 19 (SPSS; SPSS Inc., Chicago, IL, USA) and Prism 4 (GraphPad Software Inc., La Jolla, CA, USA). Permission was obtained from the Caldicott Guardian of our institution.


We studied all of the 232 women of childbearing age (18–45 years) from a total of 730 obese people who had undergone bariatric surgery during the study period. Mean ± standard deviation (SD) age was 34.0 ± 5.9 years, weight 137.7 ± 21.3 kg and BMI 50.6 ± 7.2 kg/m2 at the time of bariatric surgery. There was significant weight loss after bariatric surgery with mean %EWL of 70.2 (95% CI: 58.8–81.6) at a median 30 months of follow-up (P < 0.0001) (Figure 1).

Figure 1.

Weight loss following bariatric surgery in all women of childbearing age (open circles). %EWL, percent excess weight loss; error bars, standard error of the mean.

Twenty-one women (9.1%) became pregnant following bariatric surgery (pregnancy group). They were significantly younger at the time of surgery compared with the remaining 211 women (non-pregnancy group) but were well matched for pre-operative weight, BMI and type of bariatric procedure (Table 1). Both groups of women lost a significant amount of weight following bariatric surgery. There was no significant difference in %EWL between the pregnancy group and the non-pregnancy group (70.4% vs. 70.0%, respectively) at 30 months after surgery (Figure 2).

Figure 2.

Weight loss following bariatric surgery in women of childbearing age categorized by pregnancy (filled circles) and non-pregnancy groups (open diamonds). %EWL, percent excess weight loss; trendline, mean %EWL in all women of childbearing age; error bars, standard error of the mean.

View this table:
Table 1

Baseline characteristics and type of bariatric surgery in women of childbearing age categorized by pregnancy and non-pregnancy groups

Baseline characteristicsPregnancy group (N = 21)Non-pregnancy group (N = 211)Pa
Age at surgery (years)28.05.434.65.6<0.001
Pre-op weight (kg)136.518.5137.821.6Ns
Pre-op BMI (kg/m2)49.27.450.77.2Ns
Type of procedureN%N%Pb
  • aStudent t-test. bFisher exact test. BMI, body mass index; RYGB, Roux-en-Y gastric bypass; LAGB, laparoscopic adjustable gastric banding; LSG, laparoscopic sleeve gastrectomy; SD, standard deviation; Ns, non-significant.

Of the 21 women in the pregnancy group, 13 women (61.9%) had achieved a total of 29 recognized pregnancies (range: 1–7) between them before bariatric surgery, of which six (20.7%) resulted in spontaneous miscarriages and one (3.5%) termination of pregnancy (ToP). Following bariatric surgery, there were a total of 28 pregnancies (one of which was a twin pregnancy) between the 21 women in the post-operative study period, resulting in 24 (85.7%) completed pregnancies, 3 (10.7%) ToP and 1 (3.6%) spontaneous miscarriage.

The time interval from bariatric surgery to first pregnancy was a median 11.0 (range: 1.5–36.0) months and was planned in six women (28.6%). Eighteen of the 21 women (85.7%) completed the first pregnancy successfully. Median duration of gestation was 38 (range: 35–40) weeks. Live birth was achieved by vaginal delivery in 12 women (66.7%) and caesarean section in 6 (33.3%). The median birth weight was 2949 g (range: 2180–4390).


We analysed outcomes following bariatric surgery in a retrospective, observational cohort of women of childbearing age. Our study confirmed significant post-operative weight loss over a median 2½ years of follow-up. Furthermore, contrary to anecdotal concerns that pregnancy after bariatric surgery may thwart weight loss benefits,3 we observed no significant difference in weight loss in women who became pregnant compared with those who did not.12

Prior to bariatric surgery, two-fifths of women of childbearing age in the pregnancy group had no recognized pregnancies and the rate of early pregnancy loss was 1 in five in those who did. In contrast, the miscarriage rate post-bariatric surgery of <1 in 25 overall compares very favourably with the pre-bariatric surgery rate, as well as the 10–20% expected in the general obstetric population.13 Although infertility should not be considered as a primary indication for bariatric surgery and data on fertility problems prior to bariatric surgery were not systematically recorded in our cohort, it is well recognized that significant weight loss following bariatric surgery, resulting in improvement of conditions such as polycystic ovary syndrome, anovulation and irregular menses, leads to improved fertility rates.1 Our results are consistent with the findings of recent systematic reviews that 5–15% of women of childbearing age become pregnant after bariatric surgery and that obstetric complications in these women are less common than in matched obese controls.7,8,14,15 Despite routine pre-bariatric surgery counselling regarding pregnancy and contraception, over two-thirds of first pregnancies following bariatric surgery in our study were reported as unplanned. Although we have no recorded data on contraceptive use following bariatric surgery, other workers have reported that many women who undergo bariatric surgery do not use very effective contraceptive methods or any contraception.16 Some studies have discussed the potential for compromised absorption of oral contraceptives as a result of the anatomical and physiological alterations from malabsorptive bariatric surgery.1 However, one systematic review identified no substantial decrease in effectiveness of oral contraceptives following bariatric surgery from available studies, although evidence regarding effectiveness was limited.17

Although we did not observe surgical emergencies in any of the pregnancies in our cohort, notable surgical complications of weight loss procedures during pregnancy could include small bowel obstruction, internal hernias, gastric band erosion or migration and cholelithiasis.8,18 Small bowel obstruction is a well-recognized life-threatening late, albeit rare, complication of bariatric surgery, principally Roux-en-Y gastric bypass and commonly results from internal hernias and sometimes from volvulus or intussusceptions.3,19

Obstetric and neonatal outcomes are similar in women conceiving during or after the period of maximal weight loss following bariatric surgery.20 Nonetheless, it would be prudent to defer pregnancy for 12–18 months after bariatric surgery to reduce the potential risk of intrauterine growth retardation while allowing the woman to attain the full therapeutic benefit of the procedure.1,3,19 Close surveillance of maternal weight and nutritional status is also advisable, particularly if conception occurs in the first year after surgery.12


We conclude that weight loss outcomes after bariatric surgery in women of childbearing age are similar to that reported in the general bariatric surgical population. Pregnancy after bariatric surgery is safe and does not adversely affect weight loss. However, close monitoring of maternal weight and nutritional status is desirable, particularly if pregnancy occurs in the first 12 months after surgery.

Conflict of interest: None declared.


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