Pregnancy after bariatric surgery: a current view of maternal, obstetrical and perinatal challenges
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- Magdaleno, R., Pereira, B.G., Chaim, E.A. et al. Arch Gynecol Obstet (2012) 285: 559. doi:10.1007/s00404-011-2187-0
With the increase in the number of bariatric surgeries being performed in women of childbearing age, physicians must have concerns regarding the safety of pregnancy after bariatric surgery. The aim of this review is to summarize the literature reporting on maternal, obstetrical and perinatal implications of pregnancy following BS.
English, Spanish and Portuguese-language articles were identified in a PUBMED search from 2005 to February 2011 using the keywords for pregnancy and bariatric surgery or gastric bypass or gastric banding.
The studies show improved fertility and a reduced risk of gestational diabetes, pregnancy-induced hypertension and pre-eclampsia, macrosomia in pregnant women after bariatric surgery. The incidence of intrauterine growth restriction and small for gestational age are increased. No conclusions can be drawn concerning the risk for cesarean delivery and the best surgery-to-conception interval. Deficiencies in iron, vitamin A, vitamin B12, vitamin K, folate and calcium can result in maternal and fetal complications.
Pregnancy outcome of women who delivered after BS, as compared to obese populations, is better and safer and comparable to the general population. Close supervision before, during and after pregnancy following bariatric surgery and nutrient supplementation adapted to the patient’s individual requirements can prevent nutrition-related complications and improve maternal and fetal health.
KeywordsBariatric surgeryPregnancyPregnancy complicationsMorbid obesityWeight loss
The prevalence of obesity has reached epidemic proportions and has become a health problem worldwide, leading authorities and health professionals to intensify their efforts to promote policies and strategies that provide answers to this important problem [1–4]. Nowadays, there are around 525 million obese adults with almost twice that number overweight—which means around 1.5 billion adults are too fat . By 2015, the World Health Organization  projects approximately 2.3 billion overweight and more than 700 million obese adults.
In recent decades, there has been a clear increase in the prevalence of obesity in the European population, albeit not in the same proportion as in the USA . The recent data published by the Organization for Economic Co-operation and Development (OECD)  show an increase in the prevalence of being overweight among adolescents in European countries, leading to a greater propensity for them to develop obesity and correlated illnesses in adulthood  and to have a shorter lifespan than their parents . Among boys, the average overweight rate increased from 13% in 2001 to 17% in 2006, while among girls, the average overweight rate increased from 8 to 10% over the same period .
Amidst this epidemic, obesity among pregnant women has risen dramatically . Maternal obesity is a significant problem that will increase as general rates of obesity in the population continue to rise, and gynecologists and obstetricians will increasingly face pregnant patients suffering from obesity . Pregravid obesity and obesity in pregnancy represent a special problem, not only because of their adverse effects on maternal health and pregnancy outcome [8–12], but also because the disturbed nutritional balance in the uterus may even have lifelong deleterious effects on the developing child [13, 14].
The incidence of pregnancy-related problems increases with the severity of obesity [15, 16]; therefore, weight loss is strongly recommended before pregnancy to reduce the risk of clinical, surgical and obstetrical complications [8, 14, 16–18]. Catalano  stresses the importance of pre-conceptual weight loss because many complications of maternal obesity are determined by pre-gravid weight rather than weight gain during pregnancy.
Obese women who become pregnant have an increased incidence of obesity-related reproductive and obstetric complications, including early miscarriage, preterm labor, intrauterine fetal demise, gestational diabetes mellitus (GDM), gestational hypertension, preeclampsia, fetal macrosomia, cesarean deliveries (CD), anesthesia-related complications, postpartum hemorrhage, operative infectious morbidity, thromboembolic events and birth trauma [7, 11, 18–21]. All those factors contribute to the likelihood that an obese woman will require a longer hospital stay, with the associated implications of increased cost and inadequate resources .
Since medical therapy and lifestyle changes have limited success in maintaining long-term weight loss, bariatric surgery (BS) has become an important alternative for obese women planning pregnancy  and should be considered in the pre-conception management of morbidly obese women of childbearing age . Thus, there has been an increase of morbidly obese women of childbearing age undergoing BS, subjected to the risk of complications due to these procedures  and who need information and guidance about fertility, pregnancy and contraception [24, 25]. Nowadays, almost half of all bariatric surgical procedures are performed on women of reproductive age .
In bariatric patients, pregnancies are a significant concern due to a confluence of risk factors including weight status, potential for micronutrient deficiency and psychosocial and economic preparedness following weight-loss surgery . However, pregnancy outcome of women who delivered after BS, as compared to obese populations, is better and safer [8, 11, 12, 20, 27–32] and comparable to the general population [29, 33].
The aim of this review is to summarize the literature reporting on maternal, obstetrical and perinatal implications of pregnancy following BS.
The process involved an extensive literature review to identify studies that evaluated pregnancy in women who underwent BS. English, Spanish and Portuguese-language articles were identified by searching PubMed from 2005 to February 2011 using the keywords “pregnancy AND bariatric surgery OR gastric bypass OR gastric banding”. All studies that evaluated the relationship of pregnancy with BS through scientifically valid methodology were the subject of this review. The titles and abstracts were evaluated by the author to verify the relevance of the study for this review. The relevant studies about maternal, obstetrical and perinatal implications of pregnancy following BS were evaluated by other authors, to discuss the inclusion or exclusion in the review. Studies dealing with specific surgical and anesthetic complications of operated obese pregnant women were excluded, as were studies that focused on non-surgical therapeutics for obesity. Of the 167 articles screened, 65 were included. The references of all included studies were examined in detail: nine additional articles were collected by cross-referencing from articles identified by the search. Of the studies included, 30 were retrospective studies, 21 reviews, 13 case reports, 4 case series, 5 consensus articles and 1 chapter of a book.
The relationship between obesity and infertility is well established and is mainly attributed to changes in hormone secretion resulting in oligo-ovulation and anovulation . Weight loss is often recommended for obese women desiring pregnancy to correct ovulatory dysfunction and improve fertility [16, 32, 34], and it is not uncommon for an infertility physician to recommend a morbidly obese patient to lose a massive amount of weight before proceeding with the fertility treatment .
Many women had irregular menstrual cycles or were anovulatory prior to BS and after weight loss normalized their menstrual cycles and solved fertility problems . This can lead to surprise pregnancies, and if the patients are not ready for pregnancy after BS, they should be advised to consider contraception during their first year [20, 37, 38]. Concomitant with weight loss is a reduced occurrence of hyperandrogenism and of polycystic ovary syndrome, resulting in improved ovarian function, fertility and fecundity [10, 26, 34, 36, 39, 40], which frequently lead to a post-bypass fertility rebound .
Doblado et al.  studied five women who underwent BS followed by in vitro fertilization. They alerted to the risk of potential complications of ovarian hyperstimulation syndrome (OHSS) in pregnant women after BS, because this syndrome can lead to ascites and increase intra-abdominal pressure, potentially increasing risk of late surgical complications. They recommend that physicians should closely monitor for signs and symptoms of OHSS and maintain a high index of suspicion for internal herniation in bariatric patients with OHSS.
Hirshfeld-Cytron et al.  describe a case of a patient who underwent controlled ovarian hyperstimulation after BS, in whom empty follicle syndrome was resolved by changing the route of human chorionic gonadotropin (hCG) administration from subcutaneous to intramuscular. These authors hypothesized that the redundant skin after rapid weight loss limits the bioavailability of subcutaneous administration of hCG.
A common question among women of reproductive age who are potential candidates for BS concerns the safety and optimal timing of subsequent childbearing . The period of rapid weight loss following BS is a vulnerable time period for a pregnancy and could lead to a malnourished fetus, resulting in complications such as low birth weight or malformation [30, 44]. Rapid weight loss following surgery continues for 12–18 months, after which it generally plateaus . During this period, patients or the baby may become unhealthy in this starvation state, because the time of weight loss would coincide with the time of elevated nutritional needs of pregnancy .
Some experts suggest that women should postpone pregnancy for 24 months following BS , while others suggest that pregnancy must be delayed until after weight has stabilized, usually 12–18 months following surgery [16, 17, 46–48]. However, there are studies showing that obstetrical and neonatal outcomes are similar in women conceiving during or after the period of maximal weight loss [20, 29, 45, 49–51].
There is no strong evidence to guide how long to delay pregnancy following BS [24, 43, 49, 52]; however, experts still suggest that until the influence of pregnancy timing on post-BS perinatal outcomes is better understood, clinicians should create reproductive timelines best suited to individual needs and the typical recommended period is 1 year, coinciding with the end of the period of rapid weight loss [10, 16, 24, 43, 49, 50, 52].
Gestational weight gain (GWG)
The Institute of Medicine  published recommendations on appropriate weight gain (gold standard) during pregnancy in 2009. For underweight women (pre-pregnancy BMI <18.5 kg/m2), the recommended total weight gain is 12.5–18.0 kg; for normal weight (18.5–24.9 kg/m2), 11.5–16.0 kg; for overweight (25.0–29.9 kg/m2), 7.0–11.5 kg; and for obese women (>30.0 kg/m2), 5.0–9.0 kg.
A history of BS seems to lead to low GWG [8, 14, 20, 27, 31, 45, 51, 54]. However, adequate weight gain during pregnancy after BS is necessary and recommended to promote fetal growth. If the pregnant woman who has had BS does not gain weight or gains very little during pregnancy, the fetus is at risk of intrauterine growth retardation (IUGR), abnormalities or of being small for gestational age (SGA) . For these women, vitamin and mineral supplementation to correct or prevent deficiencies and education on nutrition during pregnancy and lactation are very important [55, 56].
Wax et al.  showed that the proportion of women gaining weight during pregnancy was lower in those who underwent BS less than 18 months before pregnancy, than in those with more than 18 months. In the Santulli study , GWG in a patient who had undergone BS was on average one-half of that observed in normal BMI women. Dao et al.  found a statistically significant difference in GWG in a group of pregnant women soon after surgery when compared with a late group: early pregnancies after BS (less than 1 year) are associated with less GWG than late pregnancies.
Nutritional deficiencies: maternal and newborn consequences
Nutritional deficiencies: maternal and newborn consequences
Microphthalmia, inferior adherent leucoma, and optic nerve hypoplasia, low birth weight, generalized hypotonia, microcephaly and eye, lung and kidney malformations, microcephaly, IUGR
Intramuscular injections, particularly in malabsorption syndromes
Neural tube defects
Intracranial fetal hemorrhage and other bleeding disorders; chondrodysplasia punctata
Vitamin K reposition
Physical and neurological developmental delay, pancytopenia with macrocytosis, cortical and subcortical atrophy
Parenteral B12 treatment
Wax et al. 
Nomura et al. 
Faintuch et al.  demonstrate that reposition of micronutrients and vitamin leads to alleviation of metabolic comorbidities, and improved normalization predicted higher birth weight. These authors found that generally energy and folate intake is sufficient, but other nutrients probably do not reach ideal levels during reposition.
Weintraub et al. , in a retrospective study, concluded that BS was not found to be an independent risk factor for fetal malformations when the mother followed recommendations about vitamin and nutrient reposition.
In conclusion, many authors strongly recommend daily iron, folate, calcium and multivitamin consumption (vitamin A, vitamin B12 and vitamin K) during pregnancy, as well as education on nutrition and close supervision in order to avoid gestational complications related to nutritional deficiencies [10, 44, 46, 55, 56, 58, 65, 71], although there are no established guidelines for dietary control in this population. Beard et al.  have made some valuable clinical suggestions, including a minimum of 60 g protein/day, 400 μg/day folate, 50–100 mg elemental iron and at least 1,000 mg calcium (maximum of 1,500 mg). There is generally good compliance with recommended multivitamin supplementation after BS; however, according to Dias , these women usually do not optimally change their dietary habits during pregnancy and compliance monitoring is imperative.
Gestational diabetes mellitus
Pregestational diabetes and GDM are significantly reduced after BS [8, 14, 22, 26, 31, 33, 56, 65, 72]. The GDM rate of 8% among pregnancies after BS is similar to the overall population-based rates, and 27% lower than in pregnancies in obese women before BS . On the other hand, Karmon and Sheiner  found that the prevalence of GDM is higher in post-operative pregnancies than in community controls, but they are in concordance with Burke et al.  when compared with obese women. In contrast to these authors, Patel et al.  found no significant difference in GDM between the bariatric patients, non-obese, obese and severely obese groups.
Sheiner et al.  found that previous BS was not associated with adverse perinatal outcome among patients with GDM and also that bariatric patients who subsequently developed GDM had neither worsening nor improvement in the outcome of the pregnancy, compared with patients not undergoing BS.
Despite these controversial findings, Burke et al.  propose that BS is the only strategy to prevent GMD in obese women.
Hypertensive disorders in pregnancy (HDP)
Lower rates of hypertensive disorders in pregnancy were found in women who underwent BS [8, 14, 24, 26, 27, 33, 51, 56]. Bennett et al.  found that women who delivered after BS had a 75% lower odds of a diagnosis of an HDP than women who had a delivery before surgery.
Ducarme et al.  found that pre-eclampsia was lower in women who underwent BS than in obese women, but there was no difference in pregnancy-induced hypertension. These are important findings because these HDP are associated with adverse perinatal outcomes, including pre-term birth and IUGR, which greatly increase perinatal morbidity and mortality .
Contrary to these authors, Patel et al.  found that rates of pre-eclampsia and pregnancy-induced hypertension did not differ between pregnancies after BS and in obese women.
The need for CD is unclear, varying widely between studies. For many authors, BS is an independent risk factor for CD compared with the general population [24, 26, 50, 56, 72, 74]. On the other hand, Burke et al.  and Ducarme et al.  found that the rate of CD was lower among women who underwent BS, than in pregnant obese women. Ducarme et al.  also observed that the rate of CD performed during labor was not different between bariatric patients and obese women, but the rate of CD performed before labor was much higher in obesity because of higher rates of maternal complications.
Rates of CD are not significantly different between pre- and post-bariatric pregnancies, which may be related to a significant reduction in fetal macrosomia following BS, which is an indication for CD [8, 29]. Weintraub et al.  found that the rate of CD was higher after BS compared with obese women before BS, but when controlling for previous CD, rates no longer remained significant.
Sheiner et al.  suppose that higher rates of CD after BS are associated with caregiver bias and not as a direct effect of surgery.
Kummer et al.  describe a case of hypoxic hepatitis in a pregnant patient after BS. Hypoxic hepatitis is a syndrome caused by decreased hepatic blood flow, which presents with a marked, but transient, increase in liver enzymes, and may masquerade as other clinical syndromes, especially in the pregnant patient. It is an uncommon complication in pregnancy, although these authors recommend meticulous physical examination and assessment of laboratory values for making a proper diagnosis and guiding management of the pathology.
Infant weight is correlated to maternal BMI [14, 62]. The high rates of low birth weight and macrosomia in obese pregnant women are probably due to higher rates of vascular complications and gestational diabetes, respectively . Studies that examine weight of infants born to mothers after BS describe the following trends: a decrease in the mean birth weight, less macrosomia, increase of SGA in neonates and increase of IUGR [8, 20, 29, 33, 51, 54, 62, 71]. These findings probably result from metabolic changes with nutritional deficiency following bariatric procedures .
Protein-calorie malnutrition and micronutrient deficits might negatively affect fetal trophism and increase the proportion of SGA . Santulli et al.  and Patel et al.  found a lower birth weight in infants born to women who had undergone BS than in infants born to women with normal BMI, whereas the studied women with BS were mostly still obese in the sample. After BS in mother, mean birth weight and the incidence of macrosomia in infants are lower compared to infants born to severely obese patients, and similar to those of non-obese and obese patients . On the other hand, Ducarme et al.  found no significant difference in mean birth weight between post-BS and control groups. Dao et al.  found no cases of macrosomia after BS in their review. When comparing newborn of patients following malabsorptive BS with newborn after restrictive procedures, the birth weight of the former was significantly higher .
Birth weight tends to normalize following appropriate mother replenishment and micronutrient reposition .
Intergenerational transmission of obesity
The prevalence of overweight and obese children born to obese mothers with substantial weight loss following BS is similar to population standards, with a significant decrease in the prevalence of obesity in the offspring conceived after surgery. These data suggest that improved maternal weight status after BS may modify epigenetic factors that could modulate weight status in the offspring .
Smith et al.  demonstrate that in children born after maternal BS, the blood lipids, all indices of insulin resistance and leptin are significantly reduced; moreover, the ghrelin level is higher. There are improvements in cardiometabolic markers sustained into adolescence, attributable to an improved intrauterine environment. These authors demonstrate that reducing the exposure of fetuses to an obesigenic in utero environment leads to a dramatic decrease in the presence of severe obesity and accompanying metabolic disturbances in children, and supports the hypothesis that obese women can transmit the disease and its comorbidities to their offspring, indicating potential intrauterine imprinting.
Final comments and recommendations
To combat reproductive complications of obesity, experts acknowledge BS as preliminarily promising in pregnancy obesity treatment . Several studies and reviews have addressed pregnancy outcomes after BS and suggested that pregnancy after BS is safe and women are not at increased risk for poor perinatal outcomes. Moreover, their risks for many obesity-related gestational complications are reduced, as long as nutrition is maintained and adherence assessed [9, 10, 24, 28, 30, 33, 47, 50, 74]. If provided with appropriate monitoring, nutritional control and efficient prenatal care, pregnancy after BS has proven to be effective and safe for both the mother and the newborn .
Thus, for the morbidly obese women and those unable to lose weight by nonsurgical means, BS should be offered at a sufficient time before a planned pregnancy to allow effective weight reduction to translate into benefit for the mother and the future child .
Nutritional multidisciplinary care and close obstetrical monitoring are needed to detect any maternal or fetal complications related to BS . Low iron and folic acid in addition to deficiencies of fat-soluble vitamins and vitamin B12 are perhaps the most important factors to consider in these pregnancies .
Controversial and established areas in pregnancy after BS
Improvement of fertility due to weight loss after BS
Pregnancy after BS is not only safe for mother and baby, but may also be less risky than pregnancy in morbidly obese patients
Close monitoring of nutritional status of pregnant women for appropriate weight gain and nourishment during pregnancy, with routine measurements of iron, folate and vitamin A, K and D serum indices, and supplementation of folate, iron, calcium, vitamin A, B12 and K and dietary protein
Reduction in risk of DMG, HDP and fetal macrosomia, and increased risk for IUGR and SGA
Specific focus on fertility counseling and contraception during the first 12 months after BS
A pregnancy conceived within the first year after surgery would increase the risk for miscarriage, malformation and low birth weight
Improved maternal weight status after surgery may modify epigenetic factors that could modulate weight status in the offspring
Lower rates of CD in women after BS
Even though pregnancy after BS seems to be safe with proper monitoring and counseling, future research should address long-term maternal and child health after pregnancies and deliveries, in terms of weight management, nutritional status and burden of long-term chronic disease. An interesting issue identified during this review is that there is no study that addresses the psychological and psychiatric aspects of pregnancy in bariatric patients, an area that requires further study.
Despite the increasing number of studies in this field, results from large cohorts of consecutive patients with pregnancies after BS are needed to confirm the findings. In future, prospective studies with adequate statistical power are needed to provide scientifically sound recommendations for the management of pregnancy after BS. It is important to note that the quality of the existing case–control and cohort studies is variable and that the available studies exhibited considerable heterogeneity. What is more, most studies are underpowered to detect possible significant differences in relevant outcomes. The danger of these methodological weaknesses is that they lead to an underreporting of maternal and fetal complications after BS.
Conflict of interest