Abstract: Does assisted reproduction, such as ovarian stimulation and/or laboratory procedures, have impact on perinatal outcomes of singleton live births compared to natural conception in couples with unexplained subfertility? SUMMARY ANSWER Compared to natural conception, singletons born after intrauterine insemination with ovarian stimulation (IUI-OS) had a lower birthweight, while singletons born after IVF had comparable birthweights, in couples with unexplained subfertility. WHAT IS KNOWN ALREADY Singletons conceived by assisted reproduction have different perinatal outcomes such as low birthweight and a higher risk of premature birth than naturally conceived singletons. This might be due to the assisted reproduction, such as laboratory procedures or the ovarian stimulation, or to an intrinsic factor in couples with subfertility. STUDY DESIGN, SIZE, DURATION We performed a prospective cohort study using the follow-up data of two randomized clinical trials performed in couples with unexplained subfertility. We evaluated perinatal outcomes of 472 live birth singletons conceived after assisted reproduction or after natural conception within the time horizon of the studies. PARTICIPANTS/MATERIALS, SETTING, METHODS To assess the possible impact of ovarian stimulation we compared the singletons conceived after IUI with FSH or clomiphene citrate (CC) and IVF in a modified natural cycle (IVF-MNC) or standard IVF with single embryo transfer (IVF-SET) to naturally conceived singletons in the same cohorts. To further look into the possible effect of the laboratory procedures, we put both IUI and IVF groups together into IUI-OS and IVF and compared both to singletons born after natural conception. We only included singletons conceived after fresh embryo transfers. The main outcome was birthweight presented as absolute weight in grams and gestational age- and gender-adjusted percentiles. We calculated differences in birthweight using regression analyses adjusted for maternal age, BMI, smoking, parity, duration of subfertility and child gender. MAIN RESULTS AND THE ROLE OF CHANCE In total, there were 472 live birth singletons. Of the 472 singleton pregnancies, 209 were conceived after IUI-OS (136 with FSH and 73 with CC as ovarian stimulation), 138 after IVF (50 after IVF-MNC and 88 after IVF-SET) and 125 were conceived naturally. Singletons conceived following IUI-FSH and IUI-CC both had lower birthweights compared to naturally conceived singletons (adjusted difference IUI-FSH −156.3 g, 95% CI −287.9 to −24.7; IUI-CC −160.3 g, 95% CI −316.7 to −3.8). When we compared IVF-MNC and IVF-SET to naturally conceived singletons, no significant difference was found (adjusted difference IVF-MNC 75.8 g, 95% CI −102.0 to 253.7; IVF-SET −10.6 g, 95% CI −159.2 to 138.1). The mean birthweight percentile was only significantly lower in the IUI-FSH group (−7.0 percentile, 95% CI −13.9 to −0.2). The IUI-CC and IVF-SET group had a lower mean percentile and the IVF-MNC group a higher mean percentile, but these groups were not significant different compared to the naturally conceived group (IUI-CC −5.1 percentile, 95% CI −13.3 to 3.0; IVF-MNC 4.4 percentile, 95% CI −4.9 to 13.6; IVF-SET −1.3 percentile, 95% CI −9.1 to 6.4). Looking at the laboratory process that took place, singletons conceived following IUI-OS had lower birthweights than naturally conceived singletons (adjusted difference −157.7 g, 95% CI −277.4 to −38.0). The IVF group had comparable birthweights with the naturally conceived group (adjusted difference 20.9 g, 95% CI −110.8 to 152.6). The mean birthweight percentile was significantly lower in the IUI-OS group compared to the natural group (−6.4 percentile, 95% CI −12.6 to −0.1). The IVF group was comparable (0.7 percentile, 95% CI −6.1 to 7.6). LIMITATIONS, REASONS FOR CAUTION The results are limited by the number of cases. The data were collected prospectively alongside the randomized controlled trials, but analyzed as treated. WIDER IMPLICATIONS OF THE FINDINGS Our data suggest IUI in a stimulated cycle may have a negative impact on the birthweight of the child and possibly on pre-eclampsia. Further research should look into the effect of different methods of ovarian stimulation on placenta pathology and pre-eclampsia in couples with unexplained subfertility using naturally conceived singletons in the unexplained population as a reference. STUDY FUNDING/COMPETING INTEREST(S) Both initial trials were supported by a grant from ZonMW, the Dutch Organization for Health Research and Development (INeS 120620027, SUPER 80-83600-98-10192). The INeS study also had a grant from Zorgverzekeraars Nederland, the Dutch association of healthcare insurers (09-003). B.W.J.M. is supported by an NHMRC investigator Grant (GNT1176437) and reports consultancy for ObsEva, Merck Merck KGaA, Guerbet and iGenomix, outside the submitted work. A.H. reports grants from Ferring Pharmaceutical company (the Netherlands), outside the submitted work. F.J.M.B. receives monetary compensation as a member of the external advisory board for Merck Serono (the Netherlands), Ferring Pharmaceutics BV (the Netherlands) and Gedeon Richter (Belgium), he receives personal fees from educational activities for Ferring BV (the Netherlands) and for advisory and consultancy work for Roche and he receives research support grants from Merck Serono and Ferring Pharmaceutics BV, outside the submitted work. The remaining authors have nothing to disclose. TRIAL REGISTRATION NUMBER INeS study Trial NL915 (NTR939); SUPER Trial NL3895 (NTR4057)

Abstract: What are the long-term outcomes after allocation to use of gonadotrophins versus clomiphene citrate (CC) with or without IUI in women with normogonadotropic anovulation and clomiphene failure? SUMMARY ANSWER About four in five women with normogonadotropic anovulation and CC failure had a live birth, with no evidence of a difference in pregnancy outcomes between the allocated groups. WHAT IS KNOWN ALREADY CC has long been used as first line treatment for ovulation induction in women with normogonadotropic anovulation. Between 2009 and 2015, a two-by-two factorial multicentre randomized clinical trial in 666 women with normogonadotropic anovulation and six cycles of CC failure was performed (M-ovin trial). This study compared a switch to gonadotrophins with continued treatment with CC for another six cycles, with or without IUI within 8 months. Switching to gonadotrophins increased the chance of conception leading to live birth by 11% over continued treatment with CC after six failed ovulatory cycles, at a cost of €15 258 per additional live birth. The addition of IUI did not significantly increase live birth rates. STUDY DESIGN, SIZE, DURATION In order to investigate the long-term outcomes of switching to gonadotrophins versus continuing treatment with CC, and undergoing IUI versus continuing with intercourse, we conducted a follow-up study. The study population comprised all women who participated in the M-ovin trial. PARTICIPANTS/MATERIALS, SETTING, METHODS The participating women were asked to complete a web-based questionnaire. The primary outcome of this study was cumulative live birth. Secondary outcomes included clinical pregnancies, multiple pregnancies, miscarriage, stillbirth, ectopic pregnancy, fertility treatments, neonatal outcomes and pregnancy complications. MAIN RESULTS AND THE ROLE OF CHANCE We approached 564 women (85%), of whom 374 (66%) responded (184 allocated to gonadotrophins; 190 to CC). After a median follow-up time of 8 years, 154 women in the gonadotrophin group had a live birth (83.7%) versus 150 women in the CC group (78.9%) (relative risk (RR) 1.06, 95% CI 0.96–1.17). A second live birth occurred in 85 of 184 women (49.0%) in the gonadotrophin group and in 85 of 190 women (44.7%) in the CC group (RR 1.03, 95% CI 0.83–1.29). Women allocated to gonadotrophins had a third live birth in 6 of 184 women (3.3%) and women allocated to CC had a third live birth in 14 of 190 women (7.4%). There were respectively 12 and 11 twins in the gonadotrophin and CC groups. The use of fertility treatments in the follow-up period was comparable between both groups. In the IUI group, a first live birth occurred in 158 of 192 women (82.3%) and while in the intercourse group, 146 of 182 women (80.2%) reached at least one live birth (RR: 1.03 95% CI 0.93–1.13; 2.13%, 95% CI −5.95, 10.21). LIMITATIONS, REASONS FOR CAUTION We have complete follow-up results for 57% of the women. There were 185 women who did not respond to the questionnaire, while 102 women had not been approached due to missing contact details. Five women had not started the original trial. WIDER IMPLICATIONS OF THE FINDINGS Women with normogonadotropic anovulation and CC failure have a high chance of reaching at least one live birth. In terms of pregnancy rates, the long-term differences between initially switching to gonadotrophins are small compared to continuing treatment with CC. STUDY FUNDING/COMPETING INTEREST(S) The original study received funding from the Dutch Organization for Health Research and Development (ZonMw number: 80-82310-97-12067). A.H. reports consultancy for development and implementation of a lifestyle App, MyFertiCoach, developed by Ferring Pharmaceutical Company. M.G. receives unrestricted grants for scientific research and education from Ferring, Merck and Guerbet. B.W.M. is supported by an NHMRC Investigatorgrant (GNT1176437). B.W.M. reports consultancy for ObsEva and Merck and travel support from Merck. All other authors have nothing to declare. TRIAL REGISTRATION NUMBER This follow-up study was registered in the OSF Register, https://osf.io/pf24m. The original M-ovin trial was registered in the Netherlands Trial Register, number NTR1449.

Abstract: What is, in couples with unexplained subfertility undergoing IUI, the impact of gonadotrophins compared to clomiphene citrate (CC) on endometrial thickness (EMT) in relation to ongoing pregnancy? SUMMARY ANSWER In women with unexplained subfertility undergoing IUI with ovarian stimulation, gonadotrophins lead to a thicker endometrium compared to CC, but this does not affect ongoing pregnancy rates. WHAT IS KNOWN ALREADY A systematic review and meta-analysis among couples with unexplained subfertility undergoing IUI with ovarian stimulation showed that women who conceived had, on average, a thicker endometrium than women who did not conceive, but this evidence is not robust due to a high level of heterogeneity. There was insufficient data to draw any conclusions on EMT and the effect on pregnancy outcomes. STUDY DESIGN, SIZE, DURATION We performed a secondary analysis of a multicentre randomized controlled superiority trial in couples with unexplained subfertility undergoing IUI with adherence to strict cancellation criteria. In total, 738 couples recruited between July 2013 and March 2016 were allocated to ovarian stimulation with gonadotrophins (n = 369) or with CC (n = 369) for a maximum of four IUI cycles. According to local protocol, recombinant FSH, urinary FSH or hMG was used. Natural conceptions and cancelled cycles were removed from this secondary analysis, as they do not provide any information on pregnancy in relation to stimulation after IUI. Ongoing pregnancy was defined as a positive heartbeat at or beyond 12 weeks of gestation. PARTICIPANTS/MATERIALS, SETTING, METHODS We first determined the difference in EMT between women randomized to gonadotrophins (75 IU) and CC (100 mg) over all cycles using a linear mixed model. We then investigated the association between EMT and ongoing pregnancy after IUI using a logistic regression model, adjusted for the allocated drug, number of dominant follicles, female age, BMI, duration of subfertility, primary or secondary subfertility, referral status, smoking status, cycle number and total motile sperm count. To conclude, we investigated the association between EMT and ongoing pregnancy by logistic regression separately in women allocated to gonadotrophins and in women allocated to CC. MAIN RESULTS AND THE ROLE OF CHANCE A total of 666 couples underwent 1968 IUI cycles. Of these, 330 couples were allocated to gonadotrophins, of which 85 conceived leading to ongoing pregnancy (rate per cycle 8.9%) and 336 couples were allocated to CC, of which 71 conceived leading to ongoing pregnancy (rate per cycle 7.0%) (relative risk (RR) 1.22, 95% CI 0.92 to 1.61). The mean EMT was 8.9 mm (SD 2.1) in women treated with gonadotrophins and 7.5 mm (SD 2.1) in women treated with CC (adjusted mean difference 1.4 mm; 95% CI: 1.1–1.7). The overall mean EMT was 8.4 mm (SD 2.2) in women that conceived leading to ongoing pregnancy and 8.2 mm (SD 2.2) in women that did not conceive (adjusted odds ratio (OR): 1.03 per 1 mm increase, 95% CI 0.95–1.12). There was no association between EMT and ongoing pregnancy in women treated with gonadotrophins or CC (OR: 1.01 per 1 mm increase, 95% CI 0.90–1.13, and 1.10 per 1 mm increase, 95% CI 0.99–1.23, respectively). LIMITATIONS, REASON FOR CAUTION Since this is a secondary analysis, the data should be interpreted prudently as secondary analyses are prone to false-positive findings or could be underpowered to show associations that the study is not primarily set up for. WIDER IMPLICATIONS OF THE FINDINGS In women with unexplained subfertility and treated with IUI, gonadotrophins lead to a significantly thicker endometrium compared to CC, but there was no evidence of a consistent association between EMT in women treated with gonadotrophins or CC and the ongoing pregnancy rate. A relatively thin endometrium after CC is therefore not a valid reason to prefer gonadotrophins as the stimulation agent in IUI for unexplained subfertility. STUDY FUNDING/COMPETING INTEREST(S) The initial trial was funded by the Netherlands Organization for Health Research and Development (ZonMw) (Health Care Efficiency Research; project number: 80-83600-98-10 192). The EudraCT number for this trial was 2013-001034-18. Prof. Dr B.W.J.M. is supported by a NHMRC Practitioner Fellowship (GNT1082548). B.W.M. reports consultancy for Merck, ObsEva and Guerbet. The other authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER NTR 4057

Abstract: (Abstracted from Hum Reprod 2020;35(7):1578–1588) The septate uterus has an estimated prevalence of 0.2% to 2.3% in women of reproductive age and is associated with impaired reproductive outcomes, the biologic basis of which is unclear. The standard-of-care treatment for septate uterus is hysteroscopic septum resection.