Bariatric surgery has become an increasingly utilized and effective approach for achieving sustainable weight loss, as well as reducing morbidities associated with severe obesity.Effects of bariatric surgery on fertility are mostly reported in small studies including small number of participants. Thus, evidence is limited and further studies are necessary to assess the effects of bariatric surgery on fertility and hormonal parameters. Females after bariatric surgery reported normalization of menstrual cycles, regular ovulation, and more often spontaneous conception. A recent systematic review investigating gonadal dysfunction in obese patients and resolution of gonadal function after bariatric surgery found that 36% of women had PCOS.This resolved in 96% of women after surgical intervention with reduction of signs of hyperandrogenemia and amelioration of menstrual anomalies due to weight loss surgery.
Obese women in reproductive age aiming to perform bariatric surgery need to be informed that after bariatric surgery, the probability to get pregnant without sufficient contraception is increased. Rapid weight loss after bariatric surgery may reduce symptoms such as anovulation or cycle irregularities. Thus, in reproductive age, pregnancies are not recommended shortly after bariatric surgery and need to be planned after the phase of maximum weight loss, as short- and long-term consequences of rapid weight loss and potential micronutritional deficiencies on the offspring are not well investigated. At least 12 to 18 months and in some publications up to 24 months or until stabilization of weight after surgery are recommended between surgery and conception. Individual progress of weight loss and weight stabilization needs to be addressed. When planning a pregnancy, regular control intervals with consultation of different specialities are recommended after bariatric surger.
Studies have shown comparable pregnancy outcomes comparing pregnant women before 12 months and thereafter. Further studies demonstrated comparable rates of gestational diabetes mellitus, pregnancy-induced hypertension, birth weight, intrauterine growth restriction (IUGR), or small-for-gestational age (SGA) offspring . However, little evidence exists about these aspects in women after bariatric surgery. After fasting in pregnancy ketonemia, increased urinary nitrogen excretion and decreased gluconeogenic amino acid production were reported, and due to physiological increases of insulin resistance in pregnancy, higher risk of ketonemia and ketonuria was suspected . Thus, weight loss in pregnancy, especially shortly after bariatric procedures, might cause significant maternal metabolic changes, which potentially affect fetal development or future disposition for healthy development and disease in offspring , which are underinvestigated so far.
If pregnancy occurs within time of maximum weight loss, short control intervals of mother and offspring are recommended with regular endocrine and metabolic examinations and documentation of general health appearance, weight curve, blood parameters, nutritional behaviour and nutritional intake, and advice. Regular obstetric investigations monitoring fetal biometry with documentation of growth and well-being of the fetus, general health appearance of the mother, and planning of further pregnancy and birth modalities are necessary. If surgery-related complications cannot be ruled out, metabolic surgeons need to be involved early. It is recommended to plan delivery in a tertiary care centre with experienced interdisciplinary teams and the availability of a neonatal intensive care unit.
Women in reproductive age after bariatric surgery should be informed about the importance of nutritional supplementation in case of an emerging pregnancy and the need of compliance regarding intake and examinations. Pregnancy planning and waiting until time after maximum weight loss and optimization of nutritional supply before conception is favourable and should be recommended to all women undergoing bariatric surgery in reproductive age.
In case of pregnancy after bariatric procedures, follow-up visits and examinations have to be performed in short intervals. If controls are missed or not scheduled, higher risk of persistent vomiting, gastrointestinal bleeding, anaemia, placental vascular disease, fetal neural tube defects, intrauterine growth retardation, or even miscarriage is reported . In women with LABG, adaption might be necessary already starting from first trimester to prevent complications such as vomiting. This so-called active gastric band management must be performed by an experienced surgeon.
Dietary advice and monitoring of food intake at regular intervals performed by trained dieticians with special knowledge of needs after bariatric procedures and experience in advising pregnant women are needed. If possible, appointments should be performed before a pregnancy and at least every trimester in pregnancy and if necessary even at closer intervals
Examinations in Pregnancy
Pregnant women after bariatric surgery need to undergo regular examinations at least every trimester at specialized facilities. It is important to check nutritional state and recognize nutritional deficiencies at an early stage and try to prevent them. Examinations also include blood sampling which should be performed at least once per trimester and include full blood count, clinical chemistry, coagulation, vitamins A, D, E, K, B12, iron status, folic acid, parathyroid hormone and protein, albumin, A1c, glucose, and TSH.
Diagnosis of Gestational Diabetes Mellitus
Several studies have demonstrated that the prevalence of GDM decreases after bariatric procedures. On the contrary, obese women have high risk of GDM throughout pregnancy: up to nearly 40%, with high incidences documented already in early pregnancy, and features of the MetSy, which might contribute to pregnancy complications. So far, the procedures that should be employed to diagnose gestational diabetes are unclear in pregnancies after bariatric surgery as several problems may arise. Depending on the type of bariatric surgery (e.g., RYGB), fast glucose absorption during an OGTT might lead to severe postabsortive hypoglycaemia. Recent evidence demonstrates difficulties in the interpretation of OGTT results as plasma glucose concentrations after oral glucose load are altered following gastric bypass and characterized by rapidly changing glucose levels as well as high risk for reactive hypoglycaemic events following glucose load. This might lead to misinterpretation of postprandial glucose levels as one-hour levels misleadingly appear too high, and two-hour levels appear too low, and thus, diagnostic alternatives to define impaired glucose tolerance in pregnancies affected by metabolic surgery need to be found. Moreover, testing of GDM might be related to serious adverse events as the dumping syndrome might occur especially in women after RYGB, omega loop, or sleeve gastrectomy. Thus, no recommendations exist so far, which advice to perform an OGTT between 24 and 28 gestational weeks to diagnose gestational diabetes mellitus in women after bariatric surgery. As an alternative to an OGTT, ACOG advised to perform home glucose monitoring for several days (i.e., about one week) with measurement of fasting and postprandial glucose levels and additional measurements if symptomatic, between 24 and 28 weeks of gestation . Another alternative is to measure capillary glucose from 14 to 16 weeks of gestation with continuation throughout pregnancy. Continuous glucose monitoring (CGM) or flash glucose monitoring (FGM) systems are an upcoming tool and of special interest as more and more easily implementable devices are available nowadays. These devices might be especially helpful in women with hypo- or hyperglycaemia at regular intervals and can help to evaluate glycaemic control. FGM was found to be safe and accurate in pregnant women with diabetes. A recently published case report described the successful use of FGM in a pregnancy after RYGB complicated by GDM and nocturnal hypoglycaemia. However, further studies are necessary to evaluate safety and accuracy of FGM in pregnant women after bariatric surgery. Overt diabetes in early pregnancy is diagnosed as recommended for nonpregnant individuals after bariatric surgery.
In pregnancy, postprandial glucose levels are important for GDM diagnosis and treatment initiation as they are associated with fetal hyperinsulinemia, fetal growth, birth weight, and abdominal circumference. Due to changes in glucose absorption after bariatric procedures, rapid postprandial plasma glucose increases followed by rapid decreases and risk for dumping syndrome occur in many patients. In pregnant women after RYGB, postprandial hypoglycaemia was reported in nearly 55% up to 90% of women after a 75 g OGTT between 24 and 28 weeks of gestation. A similar constellation exists in the diagnosis of overt diabetes before 20 weeks of gestation, which should be based upon fasting values and HbA1c. If a dumping syndrome is suspected, additional postprandial measurements beyond the 2 h measurement are necessary and recommended.
In case of a diagnosis of gestational diabetes mellitus or overt diabetes in pregnancy, the controls need to be intensified and individual therapeutic approaches need to be developed.
In general, a higher risk in obese pregnant women is well known for gestational diabetes, hypertension, preeclampsia, miscarriage, caesarean section, and stillbirth. In postbariatric surgery pregnancies, decreased risk for maternal complications was reported with approximation to risks of normal-weight women and improved neonatal outcomes compared with obese women without intervention