Pregnancy after bariatric surgeries; best time, gestational, and neonatal outcomes
Middle East Fertility Society Journal volume 28, Article number: 7 (2023)
Many studies and organizations described bases of pregnancy timing after bariatric surgeries, but there is still a need for uniform scientific evidence for accurate timing.
We aimed to assess pregnancy outcomes and neonatal findings by timing of surgery to pregnancy to compare adverse perinatal outcomes among women who underwent bariatric surgery prior to pregnancy with those who had not.
Patients and methods
We included 200 pregnant females who previously performed different bariatric surgeries. All pregnant females were divided into three groups: early group of patients who were conceived ≤ 12 months from bariatric surgery included 50 patients (25.0%), middle group of patients who were conceived from 12 to 24 months from bariatric surgery included 50 patients (25.0%) and late group of patients who were conceived > 24 months from bariatric surgery included 100 patients (50.0%).
There is a more liability to preterm deliveries in the early group in comparison with the middle and late group (P = 0.064). Gestational weight gain in the early group was lower than the middle and the late group (P = 0.002). Females in the early group have a more liability to inadequate gestational weight gain in comparison with in the middle and late group P < 0.001).
Neonatal birth weight in the early group was significantly lower than the middle and late group P < 0.001).
We supported recommendations of postponing pregnancy for more than 12 months after performing bariatric surgery which allowed stabilization of maternal weight, allowing adequate gestational weight gain, better fetal and maternal health later on.
Obesity is a public world health problem affects millions of adults every year with rising incidence, thus it becomes the commonest problem in women in reproductive age . Females were described to have maternal obesity in the case of their body mass index (BMI) before pregnancy was 30 kg/m2, which has many drawbacks on the mother and fetus as high liability of gestational diabetes, hypertension, preeclampsia, congenital anomalies and fetal death [2, 3].
Bariatric surgeries become the most effective interventions that aim to reduce maternal obesity, improve pregnancy outcomes, and reduce long term drawbacks on mother and fetus in addition to maintain long-term weight loss [4, 5].
It was found that infants of mothers who underwent bariatric surgery have some risks as being born premature, small for gestational age in addition to higher liability of neonatal intensive care unit admission [5, 6]. Previous studies showed that drawbacks of bariatric surgeries on the infants were more likely occurred if pregnancy occurs within 12 months after surgery as in such period there will be marked reduction in caloric intake and a rapid rate of weight loss which has highest risk of maternal malnutrition thus low fetal nutritional supply .
Additionally, calories loss that is followed by maternal loss of weight during early post-bariatric period of catabolism limits gestational gain of weight , gestational weight gain below 5 kg is related to higher risks of new neonates that are small for gestational age (SGA) and reduction in neonatal weight, birth length, and even head circumference .
Many studies and organizations described bases of pregnancy timing after bariatric surgeries, but there is still a need for uniform scientific evidence for accurate timing.
Recommendations of the American Association of Clinical Endocrinology, American Society for Metabolic and Bariatric Surgery and the Obesity Society were that pregnancy should be postponed for about 12–18 months after bariatric surgery , but guidelines of the American College of Obstetricians and Gynecologists increased the interval to about 24 months after bariatric surgery .
Previous studies evaluated pregnancy outcomes and neonatal findings in females who get pregnant after bariatric surgeries at variable time intervals, but their results were not generalized due to many points of weakness as small sample sizes and no sufficient evaluation of impacts of weight gain during pregnancy [9, 12,13,14].
We aimed to evaluate pregnancy outcomes and neonatal findings by timing of surgery-to pregnancy to compare adverse perinatal outcomes among women who underwent bariatric surgery prior to pregnancy with those who had not. In addition to detecting relation between different bariatric surgery subtypes and peri-conception maternal outcomes as endocrine changes, irregular menstrual cycles, fertility, miscarriages, and congenital malformations.
Patients and methods
In the present study, we include all female patients who underwent bariatric surgeries in General surgery, then conceived and delivered in Gynecology and Obstetrics Department in Zagazig University Hospitals in the period from 2016 to 2021.
We obtained ethical approval for performing the study from the local ethical committees.
All female patients who conceived and delivered after performing different types of bariatric surgeries included; Roux-en-Y gastric bypass (RYGB), one anastomosis gastric bypasses (OAGB), and sleeve gastrectomy (SG) after taking written informed consents to be included in the study.
Deliveries of all included patients occurred between May2018 and July 2021.
Pre-pregnancy BMI of all included patients was 39 (19–59). Pre-pregnancy BMI of early group of patient 34 (22–45) of middle group of patient 42 (30–59) and of late group of patients was 40 (19–59).
Patients with spontaneous abortion, surgical pregnancy termination, diabetes mellitus, multiple births, and incomplete data about course of pregnancy were excluded from the analysis.
All pregnant females were divided into three groups according to (1) time interval from bariatric surgery to conception (2) recommendations of NAM for degree of gestational weight gain .
We defined time interval from bariatric surgery to conception as number of months between the date of performed bariatric surgery and of pregnancy.
Date of conception was calculated as the “1st day of last menstrual period + 2 weeks” or as “delivery date – 40 + 2 weeks” in females who cannot exactly determined the 1st day of the last menstrual period. We categorized patients according to the time interval from bariatric surgery to conception into three groups: early group refereed to patients who get pregnant at time interval of ≤ 12 months from performed bariatric surgery, middle group refereed to patients who get pregnant at time interval of 12–24 months from performed bariatric surgery, and late group refereed to patients who get pregnant at time interval of > 24 months from performed bariatric surgery. We calculated gestational weight gain by assessment of the differences between weight in late pregnancy and weight before pregnancy in kilograms. Then, we classified weight gain as adequate, inadequate, or excessive according to recommendations of NAM .
Primary outcome variables evaluation
We evaluated gestational age at time of delivery, preterm births incidence, neonatal weight, and percentile of fetal weight-for-age using weight charts of Dutch Perined birth which were stratified for gestational age at delivery and sex in days. We defined preterm birth as < 37 weeks of gestation and defined very preterm birth as < 32 weeks of gestation according to classification World Health Organization . Then we considered LGA neonates as (> 90th percentile) and SGA neonates as (< 10th percentile).
Secondary outcome variables evaluation
We evaluated Apgar score below 7 at 5 min, neonatal hospitalization after birth, presence of any congenital anomalies, and any perinatal deaths which were excluded from the study.
We assessed any pregnancy-associated complications as gestational diabetes mellitus recently diagnosed by monitoring glucose during pregnancy, gestational hypertension recently diagnosed hypertension during pregnancy above 140/90 mmHg at 2 occasions), hypertension and proteinuria (preeclampsia), and postpartum hemorrhage of ≥ 1000 ml.
The collected data were computerized and statistically analyzed using SPSS program (Statistical Package for Social Science) version 24 and NCSS 12, LLC, USA. Data were tested for normal distribution using the Shapiro Walk test. Chi-square test (χ2) and Fisher’s exact was used to calculate difference between qualitative variables. Kruskal–Wallis test was used to calculate difference between quantitative variables in more than two groups. Post hoc test for multiple comparisons was done by using Dunn’s multiple comparison post hoc test, to indicate which groups were significantly different from each other. All statistical comparisons were two tailed with significance level of P value ≤ 0.05 indicates significant, p < 0.001 indicates highly significant difference while, P > 0.05 indicates non-significant difference.
We included 200 pregnant females who previously performed different bariatric surgeries.
The commonest performed bariatric procedure was Roux-en-Y gastric bypass (RYGB) in 121 (60.5%) patients, followed by sleeve gastrectomy in 46 (23.0%) patients and OAGB one anastomosis gastric bypass (OAGB) in 33 (16.5%) patients. The mean weight loss from bariatric surgery to pregnancy was 33 (15–59) kg at the time of conception.
Early group of patients who were conceived ≤ 12 months from bariatric surgery included 50 patients (25.0%), middle group of patients who were conceived from 12 to 24 months from bariatric surgery included 50 patients (25.0%) and late group of patients who were conceived > 24 months from bariatric surgery included 100 patients (50.0%) (Fig. 1, Tables 1, 2, and 3).
Mean time from bariatric surgery to conception was 8 ± 2.5 months, 20 ± 4.6 months, and 45 ± 15 months, respectively.
No significant differences between groups regarding pre-pregnancy data.
Pregnancy outcomes and neonatal findings according to time interval between surgery and conception (Fig. 2, Tables 2, 3, 4, and 5)
There is significant differences between groups regarding age of the patient, pre-pregnancy BMI (p < 0.001) and no significant differences between groups regarding type of performed bariatric surgical procedure.
The early group of patients has lower gestational age than the middle and late groups (272 (250–288) days versus; 277 (248–288) and 282 (245–288) p < 0.001.
The early group of patients has a more liability to preterm births than the middle and the late group (16% versus 8%, and 8%, P = 0.064).
The early group of patients has a lower gestational weight gain than the middle and the late group (− 0.9 ± 12.0 kg versus 11.2 ± 6.6 kg, and 11.0 ± 7.4 kg, P = 0.002).
The early group of patients has a more liability to inadequate gestational weight gain than the middle and late group (70.0% vs 28%, and 36%, P < 0.001), but risks of excessive weight gain was lower (8.0% vs 22%, and 25%.
Neonatal birth weight in the early group was significantly lower than the middle and late group (2973 (2300–3479) g versus 3375 (3171–3979) g and late group 3375 (3171–3979) g P < 0.001).
There are no differences in SGA neonates between both groups.
Pre-pregnancy findings, pregnancy data, and neonatal outcomes according to recommendations of NAM for gestational weight gain were detailed in Table 3.
Pregnancy-related complications as gestational diabetes mellitus (GDM) and hypertension were not related to interval between surgery and conception or to degree of gestational weight gain.
None of included patients have preeclampsia.
Postpartum hemorrhage was found in in (4%) of all included patients. Congenital defects were found in (4%) of neonates. No significant differences between the included three groups of patients regarding incidence of congenital anomalies, perinatal deaths, or admission to neonatal intensive care unit.
In the present study when we assessed the value of timing pregnancy after bariatric surgeries, we found that in the early group of patients that have conceived within 12 months gestational weight gain, gestational age at delivery, in addition to neonatal birth weight were lower than those in the middle group of patients that have conceived from 12 to 24 months from bariatric surgeries and also lower than those in the group of patients that have conceived after 24 months from bariatric surgeries, additionally we found that early preterm births were observed more frequently in the early group which was similar to results of Heusschen et al. .
Our results were different from results of previous studies that demonstrated no associations between pregnancy timing after bariatric surgeries, pregnancy, maternal or neonatal outcomes. Moreover they stated that there were no increased risks of pregnancy outcomes during the 1st 12 months after performing bariatric surgeries in comparison with later pregnancies [16,17,18,19,20].
We demonstrated that neonatal birth weight and gestational age at delivery were lower in pregnancies within 12 months post-surgery. We considered reduction in neonatal birth weight of about ± 200 g although not clinically relevant as previous studies considered it, but we showed that the lower gestational age and high incidence of preterm births in the early group are alarming.
As gestational weight gain has a direct effect on the maternal and child health, so, recommendations of NAM has been put for weight gain during pregnancy which depended on the BMI before pregnancy . In our present study, we showed that gestational gain of weight was lower in the early group who get pregnant within 12 months after performing bariatric surgery and it was below the recommendations of NAM in 75% of those patients. Our results were in line with former studies which found that gestational weight gain was more adequate in patients who conceived in more than 12 months after performing bariatric surgery [14, 19, 21].
We found that low gestational weight gain in the early group was related to a lower gestational age at delivery in addition to many preterm births of < 32 weeks, similarly results of previous studies [12, 18, 19]. Additionally some females had inadequate weight gain in the early group in the form of weight loss during pregnancy, similar results were showed by Kapadia et al. , that, obese females with weight loss during pregnancy had higher liability of SGA fetus and preterm deliveries in comparison with women who conceived late after bariatric surgery and have adequate weight gain.
All these results collectively lead to encouraging women who wish to conceive after performing bariatric surgery to postpone pregnancy until stabilization of their weight so as to decrease inadequate gestational weight gain risks and decrease fetal and maternal morbidities and risks of developing fetal metabolic syndromes later on . Our results are in line with recommendations of .
Additionally, another value of postponing pregnancy until the weight is stabilized is avoiding the bad psychological effect of (gestational) weight gain in females underwent bariatric surgeries and seeking for pregnancy.
In the present study, we tried to detect the best time of getting pregnancy in females underwent bariatric surgeries by comparing females conceived after different periods and we supported recommendations of postponing pregnancy for more than 12 months after performing bariatric surgery which allowed stabilization of maternal weight, allowing adequate gestational weight gain, better fetal and maternal health later on.
Points of strengths of the study
The main point of the study which is timing of pregnancy is not sufficiently clarified in previous studies, and out study assessed such point adequately in a prospective manner and on relatively large number of patients in childbearing period underwent bariatric surgeries.
Points of weakness and recommendations
Our study and previous studies have not assessed effect of each subtype of bariatric surgery separately which has different mechanisms with variable physiological consequences.
We recommend to perform large scale study and divide patient according to subtype of bariatric surgery.
Moreover, our study did not assess the long-term effect of bariatric surgeries on fertility and off-springs of females who underwent bariatric surgeries, so we recommend longer follow-up period to females in reproductive age before and after performing bariatric surgery in addition to following up their offspring.
Availability of data and materials
Please contact author for data requests.
Body mass index
Small for gestational age
Roux-en-Y gastric bypass
One anastomosis gastric bypasses
Gestational diabetes mellitus
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Abdou, A.M., Wasfy, M.A., Negm, M. et al. Pregnancy after bariatric surgeries; best time, gestational, and neonatal outcomes. Middle East Fertil Soc J 28, 7 (2023). https://doi.org/10.1186/s43043-023-00133-x