Morbid obesity and pregnancy outcomes after single blastocyst transfer: a retrospective, North American study

Evaluating the association of female obesity with the risk of live birth following IVF: Implications for clinical practice

Obesity is a well-established risk factor for infertility. Consequentially, women living with obesity may require fertility treatment to support them to conceive. Due to evidence suggesting obesity is also linked with poorer outcomes following in vitro fertilisation (IVF), local commissioning guidelines on assisted conception recommend a BMI of <30kg/m2 before IVF can commence. However, it is currently unclear if these guidelines are evidence based. This commentary aims to critically appraise a recent systematic review by Sermondade et al, 2019 and expand upon the implications of the findings for clinical practice.

Challenges of morbid obesity in gynecological practice

Obesity is currently a global pandemic, with increasing trends worldwide. Data from the WHO, US CDC, and the UK show an increasing trend, with 50% and 25% of the US population expected to be obese and morbidly obese by 2030. Obesity affects several aspects of health, with increased risks of cardiovascular disease, diabetes, metabolic syndrome, and several malignancies. Morbid obesity significantly impacts several aspects of female life and health, from adolescence, through the reproductive years, to the postmenopausal age group. In gynecology, there is a higher prevalence of menstrual disorders and infertility and reduced success rates of assisted reproduction; increased risk of miscarriage; pelvic organ prolapse; and endometrial, ovarian, and breast cancers. Surgery in the patient with morbid obesity is associated with several logistical challenges as well as increased surgical and peri-operative risks and increased cost. In this review, we provide an overview of the current literature, with a focus on challenges of morbid obesity in gynecological practice.

Overweight, obesity and excessive weight gain in pregnancy as risk factors for adverse pregnancy outcomes: a narrative review

The global prevalence of overweight and obesity in pregnancy is rising and this represents a significant challenge for the management of pregnancy and delivery. Women who have a pre‐pregnancy body mass index greater than 25 kg m^–2 are more likely than those with a body mass index in the ideal range (20–24.99 kg m^–2) to have problems conceiving a child and are at greater risk of miscarriage and stillbirth. All pregnancy complications are more likely with overweight, obesity and excessive gestational weight gain, including those that pose a significant threat to the lives of mothers and babies. Labour complications arise more often when pregnancies are complicated by overweight and obesity. Pregnancy is a stage of life when women have greater openness to messages about their lifestyle and health. It is also a time when they come into greater contact with health professionals. Currently management of pregnancy weight gain and the impact of overweight tends to be poor, although a number of research studies have demonstrated that appropriate interventions based around dietary change can be effective in controlling weight gain and reducing the risk of pregnancy complications. The development of individualised and flexible plans for avoiding adverse outcomes of obesity in pregnancy will require investment in training of health professionals and better integration into normal antenatal care.

Overweight and obesity before pregnancy and excessive gestational weight gain are major determinants of risk for pregnancy loss, gestational diabetes, hypertensive conditions, labour complications and maternal death.

Pregnancy is regarded as a teachable moment when women are at their most receptive to messages about their health. However, unclear guidance on diet and physical activity, weight stigma from health professionals, inexperience and reluctance among professionals about raising issues about weight, and stretched resources put the health of women and babies at risk.

Excessive weight gain in pregnancy and post‐partum weight retention compromise future fertility and increase risk for future pregnancies.

Large randomised controlled trials have had little success in addressing excessive gestational weight gain or antenatal complications. Individualised, culturally sensitive and responsive interventions appear to have greater success.

Obesity and oocyte quality: Significant implications for ART and Emerging mechanistic insights

The prevalence of obesity in adults worldwide, and specifically in women of reproductive age, is concerning given the risks to fertility posed by the increased risk of type 2 diabetes, metabolic syndrome and other non-communicable diseases. Obesity has a multi-systemic impact in female physiology that is characterized by the presence of oxidative stress, lipotoxicity, and the activation of pro-inflammatory pathways, inducing tissue-specific insulin resistance and ultimately conducive to abnormal ovarian function. A higher body mass is linked to Polycystic Ovary Syndrome, dysregulated menstrual cycles, anovulation, and longer time to pregnancy, even in ovulatory women. In the context of ART, compared to women of normal BMI, obese women have worse outcomes in every step of their journey, resulting in reduced success measured as live birth rate. Even after pregnancy is achieved, obese women have a higher chance of miscarriage, gestational diabetes, pregnancy complications, birth defects, and most worryingly, a higher risk of stillbirth and neonatal death. The potential for compounding effects of ART on pregnancy complications and infant morbidities in obese women has not been studied. There is still much debate in the field on whether these poorer outcomes are mainly driven by defects in oocyte quality, abnormal embryo development or an unaccommodating uterine environment, however the clinical evidence to date suggests a combination of all three are responsible. Animal models of maternal obesity shed light on the mechanisms underlaying the effects of obesity on the peri-conception environment, with recent findings pointing to lipotoxicity in the ovarian environment as a key driver of defects in oocytes that have not only reduced developmental competence but long-lasting effects in offspring health.

Overweight and obesity significantly reduce pregnancy, implantation, and live birth rates in women undergoing In Vitro Fertilization procedures

OBJECTIVE

The objective of this study was to evaluate the effects of overweight and obesity on fertility outcomes in IVF procedures.

METHODS

This was a retrospective and nonrandomized study that included 191 IVF/ICSI cycles using non-donor oocytes performed between July 2016 and December 2018 that were allocated according to Body Mass Index (BMI) in three groups: Normal group: 18.5-24.9 (n=67 women), Overweight group: 25.0-29.9 (n=86 women) and Obesity group: ≥30.0 (n=38 women). We compared fertilization rates, embryo quality at day 3, development and quality of blastocyst, pregnancy rates, implantation rates, and live birth rates.

RESULTS

Patients from all groups had similar stimulation days, but those women with overweight and obesity used more hormones compared to women with normal weight (p<0.05). Fertilization rates, zygotes that underwent cleavage and good-quality embryos at Day 3 were similar between the three evaluated groups. The groups of overweight and obesity had embryos at Day 3 with significantly less cells, compared to those from the normal group (p<0.05). The blastocyst development rate was significantly lower in women with overweight and obesity compared to women with normal BMI (p<0.05); but, the percentages of good blastocysts were similar in all studied patients. Pregnancy, implantation and live birth rates were significantly lower in the group of women with overweight and obesity, compared to those women with normal weight (p<0.05). Obese women had significantly more miscarriages compared to those in the other groups (p<0.05).

CONCLUSIONS

Our data shows that an increased BMI affects embryo development and significantly reduces the pregnancy, implantation and live birth rates.

The effect of weight and body mass index on serum progesterone values and live birth rate in cryopreserved in vitro fertilization cycles

Objective

To determine if weight or body mass index (BMI) affects the serum progesterone level at the time of the pregnancy test in cryopreserved blastocyst transfer cycles and to determine if those serum progesterone levels affect live births.

Design

Retrospective cohort study.

Setting

US academic medical center.

Patient(s)

Six hundred thirty-three patients undergoing their first cryopreserved embryo transfer cycle.

Intervention(s)

None.

Main Outcome Measure(s)

The primary outcome was the serum progesterone level on the day of the pregnancy test by patient weight and BMI. Our secondary analysis assessed the serum progesterone effect on live birth rate (LBR) in a clinic where progesterone supplementation was increased if the progesterone level was <15 ng/mL on the day of the pregnancy test.

Results(s)

There was a strong negative correlation between serum progesterone level and both BMI and weight, with BMI accounting for 27% and weight accounting for 29% of the variance in progesterone level. Serum progesterone level on the day of the pregnancy test was <15 ng/mL in 3% of women weighing <68 kg compared with 29% of women weighing ≥90.7 kg. Among women weighing ≥90.7 kg, live birth occurred in 47% whose serum progesterone level was <15 ng/mL on the day of the pregnancy test compared with 49% in those with serum progesterone level of 15–19 ng/mL and 44% in those with serum progesterone level of ≥20 ng/mL.

Conclusion(s)

Body weight was a significant factor in serum progesterone level at the time of the pregnancy test, with nearly 30% of patients weighing ≥90.7 kg having serum progesterone level of <15 ng/mL, a value associated with lower LBRs in prior studies. However, we found no effect of low progesterone levels on LBR after cryopreserved embryo transfer cycles in a clinic where progesterone dosing was increased if serum progesterone levels were <15 ng/mL.

Association between maternal prepregnancy body mass index and pregnancy outcomes following assisted reproductive technology: A systematic review and dose-response meta-analysis

This systematic review investigated dose-response relationship between maternal prepregnancy body mass index (BMI) and pregnancy outcomes following assisted reproductive technology, including clinical pregnancy rate (CPR), miscarriage rate (MR), and live birth rate (LBR). We searched four major databases and finally included 105 studies involving more than 271,632 pregnant women. We performed linear or nonlinear dose-response meta-analyses using random effects models. At per-woman level, pooling of unadjusted estimates shown an inverted J-shaped relationship between maternal BMI and CPR; pooling of adjusted estimates showed a linear association, suggesting statistical association between higher maternal BMI and lower CPR (adjusted OR [aOR] for 5-unit increase in BMI: 0.96, 95%CI: 0.94-0.98). At per-cycle level, linear dose-response relationship was found between maternal BMI and CPR (crude relative risk, RR, [cRR] for 5-unit increase in BMI 0.97, 0.96-0.98; aOR 0.96, 0.94-0.99). Linear dose-response relationship was established between maternal BMI and the outcomes of MR or LBR (higher BMI associated with higher MR [cRR 1.15, 1.08-1.22] and lower LBR [cRR 0.91, 0.88-0.94] at per-woman level). Sensitivity analyses showed no significant changes. In conclusion, there is dose-response relationship between maternal BMI and pregnancy outcomes following assisted reproductive technology. Higher BMI values may suggest suboptimal pregnancy outcomes.

Live birth outcomes in infertile patients with class III and class IV obesity following fresh embryo transfer

OBJECTIVE

Assess the effect of class III (body mass index [BMI, kg/m2] 40-49.9) and class IV obesity (≥ 50) on clinical pregnancy and live birth outcomes after first oocyte retrieval and fresh embryo transfer cycle.

DESIGN

Cohort study SETTING: Academic center PATIENTS: Patients undergoing their first oocyte retrieval with planned fresh embryo transfer in our clinic between 01/01/2012 and 12/31/2018. Patients were stratified by BMI: 18.5-24.9 (n = 4913), 25-29.9 (n = 1566) 30-34.9 (n = 559), 35-39.9 (n = 218), and ≥ 40 (n = 114).

INTERVENTION

None MAIN OUTCOME MEASURE: Live birth rate RESULTS: Following embryo transfer, there were no differences in pregnancy rates across all BMI groups (p value, linear trend = 0.86). However among pregnant patients, as BMI increased, a significant trend of a decreased live birth rate was observed (p value, test for linear trend = 0.004). Additionally, as BMI increased, a significant trend of an increased miscarriage rate was observed (p value, linear trend = < 0.001). Compared to the normal-weight cohort, women with a BMI ≥ 40 had a significantly higher rate of cancelled fresh transfers after retrieval (18.4% vs. 8.2%, OR 2.51; 95%CI 1.55-4.08). Among singleton deliveries, a significant trend of an increased c-section rate was identified as the BMI increased (p value, linear trend = <0.001).

CONCLUSION

Overall, patients with a BMI > 40 have worse IVF treatment outcomes compared to normal-weight patients. After embryo transfer, their pregnancy rate is comparable to normal-weight women; however, their miscarriage rate is higher, leading to a lower live birth rate for pregnant women in this population. Patients with a BMI > 40 have a c-section rate that is 50% higher than normal-weight patients.

What Are the Live Birth and Multiple Pregnancy Rates When 1 Versus 2 Low-Quality Blastocysts Are Transferred in a Cryopreserved Cycle? a Retrospective Cohort Study, Stratified for Age, Embryo Quality, and Oocyte Donor Cycles

Outcomes among women who transferred only Gardner's grade BB or lower quality frozen embryos transferred (FET) are not well known. Our objective is to study whether transferring 2 versus 1 frozen low-quality blastocysts will increase the live birth rate (LBR) and the multiple pregnancy rate (MPR). This is a retrospective cohort study including 1104 FET cycles. Only day 5-6 blastocysts of grade BB or lower quality were included. Clinical pregnancy rate (CPR), MPR, and LBR per cycle were compared between single embryo transfer (SET) (n = 969) and double embryo transfer (DET) (n = 135). CPR and MPR were compared between SET and DET in grade BB, BC, CB, and CC individually. Among SET, BB blastocysts had higher CPR 34% (P = 0.0001) and a sub-significant increase in LBR 19% (P = 0.059) in comparison to other grade SET. Among all BB, MPR was significantly higher when transferring two versus one (5.9 vs. 1.9, P = 0.009). If age at egg collection ≥ 40 years (n = 97), no difference was found in CPR (11.1 vs. 11.7, P = 0.9), MPR (0 vs. 0), and LBR (6.3 vs. 0,P = 0.13) when SET or DET was performed. If age was < 40 years (n = 818), the MPR was significantly higher in DET than SET (6.7 vs. 1.63, P = 0.004). In egg donor cycles (n = 189), there was no difference in CPR, MPR, and LBR between SET and DET. Single embryo transfer should be offered even in women ≥ 40 years of age or transferring lower quality embryos since transferring more did not increase outcomes in this group, and SET is likely the safest path.

The effect of prepregnancy body mass index on birth weight, preterm birth, cesarean section, and preeclampsia in pregnant women

Objective: The objective of this study is to determine the impact of maternal prepregnancy BMI on birth weight, preterm birth, cesarean section, and preeclampsia among pregnant women delivering singleton life birth. Methods: A cross-sectional study of 4397 women who gave singleton birth in Tehran, Iran from 6 to 21 July 2015, was conducted. Women were categorized into four groups: underweight (BMI < 18.5 kg/m2), normal (BMI 18.5-25 kg/m2), overweight (BMI 25-30 kg/m2) and obese (BMI >30 kg/m2), and their obstetric and infant outcomes were analyzed using both univariate and multivariate logistic regression. Results: Prepregnancy BMI of women classified 198 women as underweight (4.5%), 2293 normal (52.1%), 1434 overweight (32.6%), and 472 as obese (10.7%). In comparison with women of normal weight, women who were overweight or obese were at increased risk of preeclampsia (odds ratio (OR) = 1.47, 95% CI = 1.06-2.02; OR = 3.67, 95% CI = 2.57-5.24, respectively) and cesarean section (OR = 1.21, 95% CI = 1.04-1.41; OR = 1.35, 95% CI = 1.06-1.72, respectively). Infants of obese women were more likely to be macrosomic (OR = 2.43, 95% CI = 1.55-3.82). Conclusion: Prepregnancy obesity is a risk factor for macrosomia, preeclampsia, and cesarean section and need for resuscitation.

The influence of body mass index on pregnancy outcome following single-embryo transfer

PURPOSE

The association between obesity and reproductive outcome is controversial. The aim of this study is to evaluate the effects of obesity on clinical pregnancy rates following transfer of a single fresh embryo.

METHODS

A retrospective cohort study was conducted at a single tertiary medical center, including all first, fresh, single-embryo transfers using non-donor oocytes, during 2008-2013. We compared clinical pregnancy rate and pregnancy outcomes of singleton live births resulting from the transfer of a single fresh embryo in normal weight, overweight, and obese women, defined as body mass index (BMI) < 25 kg/m², ≥ 25 BMI <30 kg/m², and BMI ≥ 30 kg/m², respectively.

RESULTS

Overall, 1345 cases met the inclusion criteria with 864 single-embryo transfers (SETs) in normal weight women, 292 in overweight women, and 189 SETs in obese women, resulting in 538 clinical pregnancies and 354 singleton births. The clinical pregnancy rate per transfer was similar among the three groups (41.3, 37.6, 37.5%, respectively, p = 0.416). Similarly, there were no significant differences in live births or ongoing pregnancies. On multivariate logistic regression analysis, BMI did not impact the likelihood for clinical pregnancy (OR 0.98, 95% CI 0.96-1.008, p = 0.216).

CONCLUSIONS

Our study demonstrated that obesity has no detrimental effect on the clinical pregnancy rate resulting from the transfer of a single fresh embryo.

The correlation between raised body mass index and assisted reproductive treatment outcomes: a systematic review and meta-analysis of the evidence

Background

Public funding for fertility services within the United Kingdom is limited, and therefore, strict guidance exists regarding who can be offered treatment under the National Health Service (NHS). Body mass index (BMI) is a universal criteria adopted by both the public and private sector.

This study addresses an important aspect of the impact of a raised BMI on fertility treatment outcomes. We standardise the analysis of the data by only including studies incorporating the WHO BMI criteria; the current reference point for clinicians and clinical commissioning groups in ascertaining which group of patients should receive treatment. This study is an update of the previous systematic review performed in 2010, with the inclusion of a larger number of cycles from central databases such as the Society for Assisted Reproductive Technology (SART).

Methods

An electronic literature search was conducted through the Cochrane, Medline and Embase libraries. Data extraction for each outcome measure was pooled and expressed as an odds ratio with 95% confidence intervals. Where clinical heterogeneity was evident, the random effects model was used to calculate the risk ratio and a fixed effects model was used for the remaining studies. A p value < 0.05 was considered statistically significant.

Results

A total of 49 studies have been identified and included in this systematic review. Overweight and obese (BMI ≥ 25 kg/m²) women have a statistically significant lower live birth rate (OR 0.81, 95% CI 0.74–0.89, p < 0.00001) following Assisted Reproductive Technology (ART) when comparisons are drawn to women with a normal BMI. An increase is also demonstrated in the number of miscarriages experienced by women with a BMI ≥ 30 kg/m² (OR 1.52, 95% CI 1.28–1.81, p < 0.00001).

Conclusion

Although this review concludes that a clear impact of BMI on ART outcomes is demonstrated, there remains questions as to the pathophysiology underlying these differences. This review supports the government’s stringent criteria regarding BMI categories under which NHS funding is made available for ART, through a clear description of poor reproductive outcomes in women with a BMI ≥ 30 kg/m².

Arabian Peninsula ethnicity is associated with lower ovarian reserve and ovarian response in women undergoing fresh ICSI cycles

PURPOSE

Recent studies have demonstrated that ethnicity can be an independent determinant of assisted reproductive technology (ART) outcomes. In this context, we investigate whether ART outcomes differ between Arabian Peninsula and Caucasian women.

METHODS

This is a retrospective cohort study of women undergoing fresh intracytoplasmic sperm injection (ICSI)-embryo transfer (ET) cycles for male factor infertility. The study cohort was divided into 2 groups based on ethnicity-Arabian Peninsula or Caucasian. Ovarian reserve, ovarian response, and pregnancy outcomes were compared between the groups. A sub-analysis was performed between individual Arabian Peninsula nationalities for the same outcomes. A multiple linear regression model was used to assess the independent effect of ethnicity on ovarian response.

RESULTS

Seven hundred sixty-three patients were included-217 (28.4%) Arabian Peninsula and 546 (71.6%) Caucasian. There was no difference in the mean age of the two groups; however, the former had a higher body mass index (28.5 ± 7.5 vs. 23.3 ± 5.7; P < 0.001). Although follicle stimulating hormone (FSH) levels and antral follicle counts (AFC) were within the normal range in both groups, Arabian Peninsula women had higher FSH levels (5.7 ± 2.5 vs. 4.9 ± 2.8; P = 0.001) and lower AFC (13.9 ± 4.7 vs. 16.5 ± 4.3; P < 0.001) when compared to Caucasian women. Women from the Arabian Peninsula also had a statistically lower number of mature oocytes retrieved (15.6 ± 6.8 vs. 14.1 ± 8.4; P = 0.01), despite requiring higher gonadotropin doses. Multiple linear regression reveled that Arabian Peninsula women had 2.5 (95% CI 2.1-3.9) less mature oocytes, even after controlling for confounders. A sub-analysis within the Arab cohort demonstrated that Qatari women had a higher yield of mature oocytes when compared to Emirati, Kuwaiti, and Saudi women. There was no difference in the rates of implantation, clinical pregnancy, or live birth when comparing individual Arabian Peninsula nationalities with each other or to Caucasians.

CONCLUSIONS

Arabian Peninsula ethnicity is associated with lower ovarian reserve and ovarian response parameters in women undergoing their first ICSI-ET cycle.