Worth the wait? Preconception weight reduction in women and men with obesity and infertility: a narrative review

The Impact of Overweight and Obesity on Pregnancy: A Narrative Review of Physiological Consequences, Risks and Challenges in Prenatal Care, and Early Intervention Strategies

BACKGROUND

While substantial literature exists on the intersection of overweight/obesity (OWO) and pregnancy, much of it focuses on specific aspects, making it difficult to maintain an overview of clinically relevant factors for optimal care of OWO women throughout pregnancy.

OBJECTIVES

To provide a comprehensive synthesis of the existing literature, covering the full spectrum of clinically relevant information needed to manage OWO women from preconception to birth.

METHODS

For this narrative review a literature search was conducted on PubMed in January 2025. Eligible studies included full-text English articles with data from human subjects, with no restrictions on publication date.

FINDINGS

The impact of OWO on pregnancy is multifaceted, encompassing four interrelated themes: physiological consequences, emerging risks, challenges in prenatal care, and intervention strategies. OWO women exhibit differences in metabolic and inflammatory pathways compared to normal-weight women, reflected in altered laboratory tests. When managing gestational diabetes and preeclampsia, obesity-related characteristics must be considered. Clinicians need to be alert of obesity-mediated fetal complications, including overgrowth, malformations, stillbirth, and preterm birth, while navigating challenges in ultrasound measurements. Interventions during the preconception and prenatal periods provide key opportunities to optimize maternal weight and reduce the risk of long-term disease development.

CONCLUSION

The review's insights enhance clinical practice and call on researchers and policymakers to prioritize strategies that offer early counseling for obese pregnant women. These initiatives aim to optimize outcomes for both mother and child and contribute to combating the global obesity crisis.

Teratogenic risks of treated and untreated maternal obesity

Untreated obesity in pregnancy is associated with adverse fetal and neonatal outcomes that influence the long-term offspring health trajectory, propagating obesity and cardiometabolic disease from one generation to the next. The current efforts to reduce the risk of these negative outcomes through preconception weight loss remain largely ineffective. Anti-obesity medications (AOMs) are an understudied option for this indication, likely due to the potential for teratogenicity with accidental exposure during pregnancy. However, the current recommendation to discontinue all AOMs prior to conception fails to frame obesity within the chronic disease paradigm typically used for preconception counseling. Evolving evidence suggests that glucagon-like peptide 1 receptor agonists (GLP-1 RAs), the newest and most effective AOM class, may be safe in early pregnancy. Although further research is needed, counseling about GLP-1 RAs during pregnancy should include the potential for both risk and benefit. This review summarizes the known risks that obesity in pregnancy poses to the offspring and discusses the benefits and limitations of current treatment strategies. While there remain several barriers to optimal preconception and prenatal care for people with obesity, this review aims to arm providers with the knowledge needed for patient-centered counseling prior to and during pregnancy.

Integrated Insights into Metabolic and Bariatric Surgery: Improving Life Quality and Reducing Mortality in Obesity

Metabolic and bariatric surgery (MBS) is an effective intervention for patients with severe obesity and metabolic comorbidities, particularly when non-surgical weight loss methods prove insufficient. MBS has shown significant potential for improving quality of life and metabolic health outcomes in individuals with obesity, yet it carries inherent risks. Although these procedures offer a multifaceted approach to obesity treatment and its clinical advantages are well-documented, the limited understanding of its long-term outcomes and the role of multidisciplinary care pose challenges. With an emphasis on quality-of-life enhancements and the handling of postoperative difficulties, the present narrative review seeks to compile the most recent findings on MBS while emphasizing the value of an integrated approach to maximize patient outcomes. Effective MBS and patients' management require a collaborative team approach, involving surgeons, dietitians, psychologists, pharmacists, and other healthcare providers to address not only physiological but also psychosocial patient needs. Comparative studies demonstrate the efficacy of various MBS methods, including Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy that may considerably decrease morbidity and mortality in individuals with obesity. Future studies should target long-term patient treatment, and decision making should be aided by knowledge of obesity, comorbidity recurrence rates, and permanence of benefits.

How do BMI-restrictive policies impact women seeking NHS-funded IVF in the United Kingdom? A qualitative analysis of online forum discussions

BACKGROUND

Across the United Kingdom's National Health Service (NHS), women with a Body Mass Index (BMI) of > 30 face restrictions accessing In Vitro Fertilisation (IVF) treatment. This study asks: what are the (un)expected and (un)intended harms and consequences experienced by women restricted from accessing NHS-funded IVF due to BMI threshold criteria?

METHODS

Posts from a popular infertility online forum were collected and reflexively thematically analysed.

RESULTS

On the forum, users discussed how they struggled to lose weight, how they faced time pressures to meet BMI thresholds, and they shared knowledge on how to comply or appear compliant with BMI cut-offs. Our study found widespread moral discourses around body weight were reproduced in the forum, particularly commonplace narratives that body weight is under personal control, that people with a high BMI should 'work' to change their bodies, and that this work helps demonstrate deservingness for IVF treatment. Moralising discourses around weight were linked to the responsibilities of a hoped-for future of motherhood, as users performed deservingness through emphasising their commitment to meeting the BMI threshold.

CONCLUSION

We conclude that NHS-IVF policies in the United Kingdom do not consider the burdensome emotional and moral work placed on people seeking treatment due to inflexible upper-limit BMI criteria.

N-acetylcysteine supplementation improves endocrine-metabolism profiles and ovulation induction efficacy in polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) affects 6-20% of women worldwide, with insulin resistance and hyperinsulinemia occurring in 50-70% of patients. Hyperinsulinemia exacerbates oxidative stress, contributing to PCOS pathogenesis. N-acetylcysteine (NAC) is an antioxidant and insulin sensitizer that shows promise as a therapeutic for PCOS. Our current study aimed to investigate the effects of NAC supplementation on endocrine-metabolic parameters in PCOS mice and its effect on ovulation induction (OI) efficacy in women with PCOS.

METHODS

Female C57BL/6 mice were orally administered letrozole (LE) to induce PCOS and then randomly divided into groups receiving daily oral administration of 160 mg/kg NAC (PCOS + NAC group), 200 mg/kg metformin (PCOS + Met group), or 0.5% carboxymethyl cellulose (drug solvent) (pure PCOS group) for 12 days. Healthy female mice served as pure controls. Estrous cycles were monitored during the intervention. Metabolic and hormone levels, ovarian phenotypes, antioxidant activity in ovarian tissues, and oxidative stress levels in oocytes were assessed post-intervention. Furthermore, a pragmatic, randomized, controlled clinical study was conducted with 230 PCOS women, randomly assigned to the NAC group (1.8 g/day oral NAC, n = 115) or the control group (n = 115). Patients in both groups underwent ≤ 3 cycles of OI with sequential LE and urinary follicle-stimulating hormone (uFSH). Cycle characteristics and pregnancy outcomes were compared between groups.

RESULTS

Similar to metformin, NAC supplementation significantly improved the estrous cycles and ovarian phenotypes of PCOS mice; reduced the LH concentration, LH/FSH ratio, and T level; and increased glucose clearance and insulin sensitivity. Notably, NAC significantly reduced oocyte ROS levels and increased the mitochondrial membrane potential in PCOS mice. Additionally, NAC significantly enhanced enzymatic and nonenzymatic antioxidant activities in PCOS mouse ovaries, whereas metformin had no such effect. In the clinical trial, compared to women in the control group, women receiving NAC had significantly lower average uFSH dosage and duration (p < 0.005) and significantly greater clinical pregnancy rates per OI cycle and cumulative clinical pregnancy rates per patient (p < 0.005).

CONCLUSION

NAC supplementation improved endocrine-metabolic parameters in PCOS mice and significantly enhanced OI efficacy with sequential LE and uFSH in women with PCOS. Therefore, NAC could be a valuable adjuvant in OI for women with PCOS.

Fecundity and Nutrient Deficiency Following Obesity Treatment: Implications for Young-Onset Cancer Risk in Offspring

Young-onset adult cancers have been an emerging problem over the last three decades in Australia [...].

Weight Regain following Bariatric Surgery and in vitro Fertilization Outcomes

INTRODUCTION

The aim of this study was to estimate the time to pregnancy and live birth and evaluate the effect of weight regain in women with a history of bariatric surgery (BS) who underwent in vitro fertilization (IVF) treatments.

METHODS

This is a retrospective cohort study. All patients with previous BS who underwent IVF treatment in a tertiary university-affiliated hospital between 2013 and 2022 were included. Time to pregnancy and live birth were compared between patients who regained less than or greater than three points of body mass index (BMI) from the nadir weight after BS. Kaplan-Meier curves and log-rank tests were used to compare groups.

RESULTS

A total of 78 patients were included in this study. The positive β-hCG, clinical pregnancy, and live birth rates following BS were 89.4%, 78.9%, and 50.8%, respectively. The median time from the beginning of IVF treatments to a positive β-hCG test was 2.97 months (95% CI: 1.04-4.89 months), to a clinical pregnancy was 7.1 months (95% CI: 3.56-10.91), and to a live birth was 20.2 months. Women who maintained their nadir BMI following BS had nearly twice the chance of achieving a clinical pregnancy (HR 1.967, 95% CI: 1.026-3.771, p = 0.042) and were approximately three times more likely to achieve a live birth (2.864, 95% CI: 1.196-6.859, p = 0.018) than those who regained at least three points of BMI.

CONCLUSION

Weight regain after BS is associated with a lower rate of live births and prolonged time to achieve clinical pregnancy and live birth.

Treating obesity and fertility in the era of glucagon-like peptide 1 receptor agonists

The objective of this narrative review is to advocate for improved comprehensive care of patients with obesity and infertility. Persons with an increased body mass index have less successful reproductive outcomes, and recently, new medications to treat neuroendocrine hormone imbalances are producing meaningful weight loss akin to surgical interventions. For the first time, obesity is publicly being recognized as a disease. These medications contain the newest generation of glucagon-like peptide 1 receptor agonists and deserve our attention for several reasons: regardless of body mass index, many patients will be using them; it is necessary to understand the mode of action, side effects, and implications for anesthetic procedures and pregnancy; and it is important to evaluate when they could be used to improve health outcomes and/or access to fertility care.

Addressing weight bias in reproductive medicine: a call to revisit body mass index restrictions for in vitro fertilization treatment

The prevalence of obesity has doubled among reproductive-age adults in the US over the past 40 years and is projected to impact half of the population by 2030. Obesity is associated with a twofold to threefold increase in infertility, largely because of anovulation, and is associated with a lower rate of pregnancy with ovulation induction among anovulatory women. As a result of these trends and associations, in vitro fertilization (IVF) care will need to be adapted to provide safe, effective, and equitable access for patients with obesity. Research over the past 10 years has demonstrated safe sedation practices and effective procedure modifications for oocyte retrievals and embryo transfers in patients with obesity undergoing IVF treatment. We encourage IVF medical directors to revisit body mass index restrictions for IVF treatment in favor of individualized patient risk assessments to minimize weight bias and provide timely access to safe and effective IVF care for patients with obesity and infertility.

Impact of bariatric surgery, lifestyle change, and pharmacotherapy on fertility in men with obesity: a systematic review protocol

OBJECTIVE

This review will determine whether various health interventions designed to reduce weight (lifestyle change, bariatric surgery, pharmacotherapy) in men with obesity are associated with improved fertility markers. The review will also establish whether the degree of weight loss achieved through these methods is associated with improvement.

INTRODUCTION

Current preconception guidelines provide limited information for men with obesity. Small studies implementing lifestyle changes in men are associated with improvement in sperm quality, whereas bariatric surgery has not been associated with improvements in sperm quality. Determining the benefit of different interventions and the relationship to weight lost is necessary to optimize male fertility.

INCLUSION CRITERIA

The population will be men younger than 50 years with overweight (BMI >25 kg/m 2 ) or obesity (BMI >30 kg/m 2 ). The exposure of interest will be an intervention undertaken to improve health or reduce weight, categorized as lifestyle change, bariatric surgery, or pharmacotherapy. Outcomes will include time to conception, fecundity rate, assisted reproduction outcomes, and semen quality measures. Secondary analysis will determine whether degree of weight loss achieved is associated with degree of improvement.

METHODS

This review will follow the JBI methodology for systematic reviews of etiology and risk. Databases to be searched will include PubMed, Embase (Ovid), Cochrane Central Register of Controlled Trials, Web of Science Core Collection, and Scopus. Articles not published or translated into English will be excluded. Methodological quality will be assessed using the JBI critical appraisal tools. Data will be extracted using a tool developed by the reviewers. Statistical meta-analysis will be performed where possible to synthesize outcomes of similar methods.

REVIEW REGISTRATION

PROSPERO CRD42022349665.

Association of overweight and obesity with cumulative live birth rates according to women's age: A cohort study of 26 567 treatment cycles

OBJECTIVE

To evaluate the effect of age on the association between maternal body mass index (BMI) and cumulative live birth rates (CLBRs) following in vitro fertilization treatment.

METHOD

We retrospectively analyzed the data of 26 567 women undergoing in vitro fertilization/intracytoplasmic sperm injection from 2016 to 2019. We conducted multivariate regression analysis of the association between CLBRs and maternal BMI and age category.

RESULTS

A total of 16 626 (62.58%) patients achieved a live birth. Women with obesity had significantly decreased CLBRs compared with women who had normal weight (odds ratio [OR] 0.73 [95% confidence interval (CI), 0.66-0.80]). The significant interaction between age and BMI suggested that the impact of BMI on CLBRs was moderated by women's age (P interaction <0.001). The association between obesity and CLBRs was inverse among women aged <30 years (OR, 0.63 [95% CI, 0.54-0.73]), 30 to 34 years (OR, 0.79 [95% CI, 0.67-0.93]), and 35 to 37 years (OR, 0.71 [95% CI, 0.52-0.98]); however, decreases in CLBRs with obesity were not observed in women aged 38 to 40 years (OR, 1.17 [95% CI, 0.70-1.94]) and ≥ 41 years (OR, 1.25 [95% CI, 0.53-2.96]).

CONCLUSION

Maternal obesity was significantly associated with a lower likelihood of having a live birth, but the risk differed according to women's age. A higher BMI might have a less-pronounced detrimental effect with increasing age.

Moderate and increased physical activity is not detrimental to live birth rates among women with unexplained infertility and obesity

Objective

To determine if moderate physical activity is associated with live birth rates in women with unexplained infertility and obesity.

Design

Secondary analysis of the Improving Reproductive Fitness through Pretreatment with Lifestyle Modification in Obese Women with Unexplained Infertility trial.

Setting

US fertility centers, 2015-2019.

Patients

A total of 379 women participated in Improving Reproductive Fitness through Pretreatment with Lifestyle Modification in Obese Women with Unexplained Infertility trial, a lifestyle modification program with increased physical activity (phase I, 16 weeks) and up to three cycles of clomiphene citrate treatment and intrauterine insemination (phase II).

Interventions

Participants were instructed to add 500 steps/day weekly until a maximum of 10,000 steps/day was reached and maintained. Participants were stratified as active (top third, N = 125) and less active (lower third, N = 125) on the basis of the average number of steps per day recorded using a FitBit activity tracker.

Main Outcome Measures

Live birth rate.

Results

Active participants were more physically active at the time of enrollment than less active participants (average baseline steps per day, 8,708 [7,079-10,000] vs. 4,695 [3,844-5,811]; P ≤ 0.001) and were more likely to reach 10,000 steps/day than less active participants (average steps per day, 10,526 [9,481-11,810] vs. 6,442 [4,644-7,747]; P ≤ 0.001), although both groups increased their average steps per day by a similar amount (1,818 vs.1,747; P = 0.57). There was no difference in live birth rates (24/125 [19.2%] vs. 25/125 [20%]; P = 0.87) between active and less active participants nor were there differences in clinical pregnancy rates (P = 0.45) or miscarriage rates (P = 0.49) between the two groups.

Conclusions

Active participants were more likely to achieve the physical activity goal, although this was not associated with benefit or harm with respect to live birth.

Clinical Trial Registration Number

ClinicalTrials.gov (NCT02432209), first posted: May 4, 2015.

Obesity and In Vitro Fertilization

Obesity is a highly prevalent chronic disease with a significant effect on reproductive-age women. The clinical implications of obesity on fertility and pregnancy are well studied citing ovulatory dysfunction, hormonal imbalances, higher miscarriage rates, and increased maternal and neonatal risks. For this reason, many patients with obesity seek reproductive specialists to help build their families. Despite this literature base, the effect of weight loss interventions prior to assisted reproductive technology (ART) is lacking. This review aims to outline the impact of obesity on ART, specifically in vitro fertilization (IVF). Response differences to treatment protocols compared with normal weight counterparts, limitations of access to care, and the mixed results of weight-reduction strategies prior to fertility treatment will be addressed. The known data surrounding benefits of lifestyle modification, pharmacologic therapies, and surgical interventions for obesity prior to IVF are outlined and found to emphasize a need for further research to determine the optimal approach for infertility patients with obesity.

Navigating the Role of Anti-Obesity Agents Prior to Pregnancy: A Narrative Review

Utilization of anti-obesity agents is rising in reproductive-age females with some planning for future pregnancy. Lifestyle-induced weight loss has been shown to increase spontaneous conception rate, improve rates of fertility intervention complications, and decrease pregnancy comorbidities. However, the definitive role of assisting weight loss with medication prior to pregnancy remains to be established. The implications of anti-obesity agent used prior to pregnancy are explored in this narrative review, considering benefits of weight loss as well as available evidence for use and risks of anti-obesity agents prior to pregnancy.

Fertility outcomes following bariatric surgery

Obesity impacts human health in more than one way. The influence of obesity on human reproduction and fertility has been extensively examined. Bariatric surgery (BS) has been used as an effective tool to achieve long-term weight loss in both sexes. BS improves hormonal profiling, increasing the odds of spontaneous pregnancy and success rates following assisted reproductive techniques in infertile females. For obese males, BS does improve sexual function and hormonal profile; however, conflicting reports discuss reduced sperm parameters following BS. Although the benefits of BS in the fertility field are acknowledged, many areas call for further research, like choosing the safest surgical techniques, determining the optimal timing to get pregnant, and resolving the uncertainty of sperm parameters.