Outcomes of In-vitro Fertilization After Bariatric Surgery

A National Register-based Case-control Study

E. Nilsson-Condori; K. Mattsson; A. Thurin-Kjellberg; J.L. Hedenbro; B. Friberg


Hum Reprod. 2022;37(10):2474-2481. 

In This Article

Abstract and Introduction


Study Question: Does previous bariatric surgery (BS) in women affect cumulative live birth rate in IVF?

Summary Answer: Women having had BS seem to have the same cumulative live birth rate as non-operated women of the same BMI at IVF treatment.

What is Known Already: Because of the perinatal risks of obesity to mother and infant as well as impaired outcomes of IVF, obese women are advised to reduce their weight, but it is not clear whether previous BS could affect IVF results.

Study Design, Size, Duration: This national register-based case–control study included all cases of BS (n = 30 436) undergoing IVF (n = 153) from 2007 until 2017.

Participants/Materials, Setting, Methods: Swedish women between 18 and 45 years operated with BS, with at least one first started cycle of IVF after surgery, were included. For each woman having IVF after BS (n = 153), up to five non-operated control women (n = 744) starting their first IVF cycle during the study period were matched for age, parity and BMI at treatment. The primary outcome in this study was the cumulative live birth rate (CLBR) after the first IVF cycle, defined as all live births after the first cycle including fresh and frozen embryo transfers.

Main Results and the Role of Chance: There was no significant difference in CLBR between the BS group and the matched controls (29.4% compared to 33.1%), even though the number of retrieved oocytes (7.6 vs 8.9, P = 0.005) and frozen embryos (1.0 vs 1.5, P = 0.041) were significantly fewer in the BS group. There was no association between cumulative live birth and BS, adjusted odds ratio 1.04, 95% CI (0.73, 1.51). However, the birth weight was significantly lower in the children born to mothers with previous BS, mean (SD) 3190 (690) vs 3478 (729) g, P = 0.037.

Limitations, Reasons for Caution: Confounders such as age, BMI and previous childbirth were accounted for by the matching design of the study, but there were no data on indication for IVF, anti-Müllerian hormone, smoking or previous comorbidities. The study was exploratory and did not reach sufficient power to detect potential smaller differences in live birth rates.

Wider Implications of the Findings: The findings concur with those in previously published smaller studies and provide somewhat reassuring results considering IVF outcomes after BS with a CLBR comparable to that of controls, despite a lower mean birth weight.

Study Funding/Competing Interest(S): This research was funded by grants from the Southern Health Care Region of Sweden. The authors have no competing interests to declare.

Trial Registration Number: N/A.


Over the past decades, obesity, defined as BMI above 30, has increased worldwide, and in Sweden, the prevalence is around 14% in women aged 30–44 years (Public Health Agency of Sweden, 2020; WHO, 2022). The pregnancy rate is lower in women with obesity, and obesity is associated with a doubled time to pregnancy as compared with normal weight women, for couples trying to conceive spontaneously (Hassan and Killick, 2004). When seeking medical care for involuntary childlessness, obesity is also associated with poorer outcomes of in-vitro fertilization (IVF) such as implantation failure, pregnancy loss and overall lower live birth rates compared to women with normal weight (ASRM, 2015; Sermondade et al., 2019). Because of this, and the perinatal risks of obesity to mother and infant, Swedish clinics apply BMI limits for access to fertility care and patients are advised to reduce their weight (Legro, 2016). Bariatric surgery (BS) with its beneficial metabolic consequences (Herzog et al., 2020) is the most effective treatment for obesity (Maciejewski et al., 2016), with large numbers of reproductive age women seeking treatment (Scandinavian Obesity Surgery Registry, SOReg, 2020). Women seem to have high expectations on regained fertility (Nilsson-Condori et al., 2019), and several studies are pointing towards increased fertility among women having gone through BS (Milone et al., 2016), in particular in women with PCOS (Benito et al., 2020). However, obesity-related infertility is not considered an indication for BS (ACOG, 2009; ASRM, 2015).

Anti-Müllerian hormone (AMH), a marker of ovarian reserve, is positively correlated with the number of retrieved oocytes and cumulative live birth rate (CLBR) after IVF (Hu et al., 2020). However, several studies have shown lower AMH levels after BS (Chiofalo et al., 2017; Nilsson-Condori et al., 2018; Vincentelli et al., 2018), and it is not clear whether previous BS could negatively impact the results of IVF. Two large randomized controlled studies on changes in lifestyle and diet in obese women before going through IVF (Mutsaerts et al., 2016; Einarsson et al., 2017) have also failed to show significant improvements in live birth rates despite substantial weight loss. In addition, IVF and BS are associated with an increased risk of adverse birth outcomes, such as preterm birth (PTB) (Johansson et al., 2015; Ginström Ernstad et al., 2016). Previous studies on IVF after BS are few and include few patients after BS (Tsur et al., 2014; Milone et al., 2017; Grzegorczyk-Martin et al., 2020). Findings include a decreased need of gonadotropins and a shorter length of stimulation, and the largest study (Grzegorczyk-Martin et al., 2020) (n = 83 patients with previous BS) found no difference in CLBR after IVF when compared to non-operated matched controls.

The aim of this study was to investigate whether outcomes of IVF differ between women with a history of BS compared with non-operated control women matched for post-surgery BMI.