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Why is the rate of teen childbearing is so unusually high in the United States as a whole, and in some U.S. states in particular? U.S. teens are two and a half times as likely to give birth as compared to teens in Canada, around four times as likely as teens in Germany or Norway, and almost ten times as likely as teens in Switzerland. A teenage girl in Mississippi is four times more likely to give birth than a teenage girl in New Hampshire—and 15 times more likely to give birth as a teen compared to a teenage girl in Switzerland. We examine teen birth rates alongside pregnancy, abortion, and “shotgun” marriage rates as well as the antecedent behaviors of sexual activity and contraceptive use. We demonstrate that variation in income inequality across U.S. states and developed countries can explain a sizable share of the geographic variation in teen childbearing. Our reading of the totality of evidence leads us to conclude that being on a low economic trajectory in life leads many teenage girls to have children while they are young and unmarried. Teen childbearing is explained by the low economic trajectory but is not an additional cause of later difficulties in life. Surprisingly, teen birth itself does not appear to have much direct economic consequence. Our view is that teen childbearing is so high in the United States because of underlying social and economic problems. It reflects a decision among a set of girls to “drop-out” of the economic mainstream; they choose nonmarital motherhood at a young age instead of investing in their own economic progress because they feel they have little chance of advancement.

Background Globally, there is no conclusive data on the pregnancy outcomes of patients with recurrent implantation failure (RIF) who received the next embryo transfer. The purpose of this study is to summarize the pregnancy outcomes of patients with RIF after embryo transfer and understand the disease burden of patients with RIF. Methods We searched for literature from databases such as PubMed, Web of Science, Embase, and Cochrane Central Register of Controlled Trials from inception to May 19, 2024, and extracted the pregnancy outcomes of patients with RIF in the blank control group, including implantation rate (IR), clinical pregnancy rate (CPR), ongoing pregnancy rate (OPR), miscarriage rate (MR), live birth rate (LBR), and ectopic pregnancy rate (EPR). Subsequently, meta-analyses of the rates were summarized and subgroup analyses were performed based on implantation failures, embryo type, fresh/frozen embryo transfer and regions. Results A total of 110 studies (14,159 patients) were included in the meta-analysis. Globally, the overall IR, CPR, OPR, MR, LBR, and EPR of patients with RIF were 19.3%, 29.4%, 24.6%, 19.9%, 23.0%, and 0.9%, respectively. No differences in pregnancy outcomes were found between RIF patients with three or more implantation failures and those with two or more implantation failures. RIF patients who transferred blastocyst achieved significantly higher IR, higher CPR, higher OPR, higher LBR and lower EPR, but no lower MR. There are differences in IR and CPR among patients with RIF in different regions, and no significant differences in other pregnancy outcomes. Conclusion This study summarizes the global pregnancy outcomes of patients with RIF who undergo subsequent embryo transfer. Pregnancy outcomes in patients with RIF may not be related to the number of implantation failures. Frozen blastocyst transfer is recommended for patients with RIF. Pregnancy outcomes in patients with RIF vary across regions. Protocol registration This study has been registered on PROSPERO (CRD 42024539968).

Purpose The objective of this study was to evaluate the efficacy of preimplantation genetic testing for aneuploidy (PGT-A) in reducing the incidence of early miscarriage among patients diagnosed with unexplained recurrent spontaneous abortion (URSA). Methods This investigation was designed as a retrospective cohort study, examining patients who underwent freeze–thaw embryo transfer (FET) of single blastocysts from January 2018 to August 2023. A total of 675 FET cycles involving patients with URSA were included in the study. The primary outcome measure was the early miscarriage rate, while secondary outcome measures included the clinical pregnancy rate, ongoing pregnancy rate, and live birth rate. Results A total of 316 patients with URSA who underwent PGT-A utilizing next-generation sequencing (NGS) technology were designated as the PGT-A group. Additionally, 359 URSA patients who underwent in vitro fertilization (IVF)/intra-cytoplasmic sperm injection (ICSI) during the same time frame were selected as the control group. Following comprehensive embryo cryopreservation, the blastocyst exhibiting the highest morphological score was chosen for the initial FET cycle in both groups. The pregnancy outcomes between the two groups were subsequently compared. In patients with URSA, the application of PGT-A was associated with improved clinical pregnancy rates (64.2% vs. 45.7%; aOR, 2.012; 95% CI, 1.303 to 3.108; P  = 0.002), ongoing pregnancy rates (53.2% vs. 34.0%; aOR, 2.121; 95% CI, 1.379 to 3.260; P  = 0.001), and live birth rates (51.3% vs. 32.9%; aOR, 2.019; 95% CI, 1.316 to 3.097; P  = 0.001). In patients aged 38 years and older with unexplained recurrent miscarriages, PGT-A not only increased the rate of ongoing pregnancies (50.0% vs. 17.5%; aOR, 4.325; 95% CI, 1.31 to 14.281; P  = 0.016) and live birth rates (46.7% vs. 17.5%; aOR, 3.684; 95% CI, 1.141 to 11.893; P  = 0.029), but also significantly reduced the rate of early miscarriage (16.7% vs. 40.0%; aOR, 0.098; 95% CI, 0.01 to 0.956; P  = 0.046). Conclusions PGT-A has been demonstrated to enhance clinical pregnancy rates, ongoing pregnancy rates, and live birth rates in patients experiencing unexplained recurrent miscarriages. Furthermore, the implementation of PGT-A significantly reduced the rate of early miscarriage among older patients aged 38 years and above.

This retrospective study aimed to compare the outcomes of day 3 double embryo transfer (DET) with single blastocyst transfer (SBT) during frozen embryo transfer (FET) cycles. A total of 999 women below the age of 38 years who underwent FET at Malaysia's KL Fertility and Gynaecology Centre from January 2019 to December 2021 were analyzed. Patients with autologous eggs were recruited in the study. All the eggs were inseminated by intracytoplasmic sperm injection. The embryos were vitrified on day 3 cleavage-stage or blastocyst stage with Cryotop® method. The FET was performed following natural cycle (NC), modified natural cycle (m-NC), or hormone replacement therapy (HRT) cycles. The NC and m-NC groups received oral dydrogesterone for luteal phase support. There were no statistical differences in the rates of positive pregnancy, clinical pregnancy, and ongoing pregnancy between the two groups. However, implantation rates were significantly higher in the SBT group (50.1% versus 37.6%, p < 0.05). The day 3 DET group had significantly higher multiple pregnancy rates (28.7% versus 1.1%, p < 0.05). Subgroup analysis of embryo transfers performed following NC, m-NC, or HRT cycles showed similar results. This study suggests that SBT is the better choice for embryo transfers as it had higher implantation rates and its pregnancy rates were similar to day 3 DET. The SBT also significantly reduced the incidence of multiple pregnancies without compromising pregnancy rates.

PurposeTo compare the pregnancy outcomes between four regimens of luteal phase support (LPS), including vaginal progesterone, oral dydrogesterone, combination of oral dydrogesterone and gonadotropin releasing hormone analog (GnRH-α), and combination of oral dydrogesterone and human chorionic gonadotrophin (hCG), in Frozen-thawed Embryo Transfer (FET) cycles.MethodsThis randomized clinical trial was performed during a 6-month period, including candidates for FET. Patients were randomly assigned to four groups for LPS: 400 mg vaginal progesterone suppository twice daily, 10 mg oral dydrogesterone twice daily, 10 mg oral dydrogesterone twice daily combined with injection of 0.1 mg GnRH-α, and 10 mg oral dydrogesterone twice daily combined with injection of 1500 IU hCG. Primary endpoint included clinical pregnancy rate, ongoing pregnancy rate (OPR), and miscarriage rate (MR).ResultsA total of 400 FET cycles were analyzed. CPR was significantly lower in dydrogesterone group (9 %) when compared to vaginal progesterone (20 %), dydrogesterone and GnRH-α (25 %), and dydrogesterone and hCG (17 %). Logistic regression showed that only dydrogesterone group had significantly lower CPR in comparison with vaginal progesterone (OR = 0.39; p = 0.03), while it was comparable between other three groups. There were no significant difference between four groups regarding to OPR and MR.ConclusionVaginal progesterone provides appropriate LPS. Yet, combination of oral dydrogesterone and GnRH-α or hCG can be more suitable option compared to vaginal progesterone for LPS in women with vaginal irritation or discharge at a lower cost.

Purpose To determine if blastocyst transfer increases the ongoing and cumulative pregnancy rates, compared with day 3 embryo transfer, in women of all ages when at least 4 zygotes are obtained. Methods Prospective study including patients undergoing a first IVF/ICSI treatment and assigned to cleavage stage ( n  = 46) or blastocyst ( n  = 58) embryo transfer. Supernumerary embryos were vitrified and patients failing to achieve an ongoing pregnancy after fresh embryo transfer would go through cryopreserved cycles. The main outcome measure was the ongoing pregnancy rate after the fresh IVF/ICSI transfer and the cumulative ongoing pregnancy rate. Results were also analyzed according to age (under 35 and 35 or older). Results A majority of patients (96.6 %) had a blastocyst transfer when at least 4 zygotes were obtained. The ongoing pregnancy rate was significantly higher in the day-5 group compared with the day-3 group (43.1 % vs. 24 %, p  = 0.041). The cumulative ongoing pregnancy rate was higher (but not significantly) with blastocyst than with cleavage stage embryos (56.8 % vs. 43.4 %, p  = 0.174). When analysed by age, patients 35 or older showed significantly higher ongoing pregnancy rate (48.4 % vs. 19.3 %, p  = 0.016) and cumulative ongoing pregnancy rate (58 % vs. 25.8 %, p  = 0.01) in the day-5 group compared to the day-3 group, while no such differences were observed in women under 35. Conclusions Blastocyst transfer can be suggested whenever there are at least 4 zygotes. While there are no differences in women under 35, the benefit of this option over cleavage stage transfer could be significant in women 35 or older.

Objective The objective of this retrospective cohort study is to investigate the impact of monitoring serum estradiol (E2) levels before progesterone administration within hormone replacement therapy (HRT) on pregnancy outcomes in women undergoing frozen-thawed embryo transfer (FET). Methods Analyzed HRT-FET cycles conducted at a reproductive center from 2017 to 2022. Serum E2 levels were measured prior to progesterone administration. Multivariate stratified and logistic regression analyses were performed on 26,194 patients grouped according to terciles of serum E2 levels before progesterone administration. Results The clinical pregnancy rate (CPR) and live birth rate (LBR) exhibited a gradual decline with increasing serum E2 levels across the three E2 groups. Even after controlling for potential confounders, including female age, body mass index, infertility diagnosis, cycle category, number of embryos transferred, fertilization method, indication for infertility, and endometrial thickness, both CPR and LBR persistently showed a gradual decrease as serum E2 levels increased within the three E2 groups. The same results were obtained by multivariate logistic regression analysis. Conclusions This large retrospective study indicates that elevated serum E2 levels before progesterone administration during HRT-FET cycles are associated with reduced CPR and LBR post-embryo transfer. Therefore, it is advisable to monitor serum E2 levels and adjust treatment strategies accordingly to maximize patient outcomes.

Background Low vitamin D status has been associated with an increased risk for infertility. Recent evidence regarding the efficacy of vitamin D supplementation in improving reproductive outcomes is inconsistent. Therefore, this systematic review was conducted to investigate whether vitamin D supplementation could improve the reproductive outcomes of infertile patients and evaluate how the parameters of vitamin D supplementation affected the clinical pregnancy rate. Methods We searched seven electronic databases (CNKI, Cqvip, Wanfang, PubMed, Medline, Embase, and Cochrane Library) up to March 2022. Randomized and cohort studies were collected to assess the reproductive outcomes difference between the intervention (vitamin D) vs. the control (placebo or none). Mantel-Haenszel random effects models were used. Effects were reported as odds ratio (OR) and their 95% confidence interval (CI). PROSPERO database registration number: CRD42022304018. Results Twelve eligible studies ( n  = 2352) were included: 9 randomized controlled trials (RCTs, n  = 1677) and 3 cohort studies ( n  = 675). Pooled results indicated that infertile women treated with vitamin D had a significantly increased clinical pregnancy rate compared with the control group (OR: 1.70, 95% CI: 1.24–2.34; I 2  = 63%, P  = 0.001). However, the implantation, biochemical pregnancy, miscarriage, and multiple pregnancy rates had no significant difference (OR: 1.86, 95% CI: 1.00–3.47; I 2  = 85%, P  = 0.05; OR: 1.49; 0.98–2.26; I 2  = 63%, P  = 0.06; OR: 0.98, 95% CI: 0.63–1.53; I 2  = 0%, P  = 0.94 and OR: 3.64, 95% CI: 0.58–11.98; I 2  = 68%, P  = 0.21). The improvement of clinical pregnancy rate in the intervention group was influenced by the vitamin D level of patients, drug type, the total vitamin D dosage, the duration, administration frequency, and daily dosage of vitamin D supplementation. The infertile women (vitamin D level < 30 ng/mL) treated with the multicomponent drugs including vitamin D (10,000–50,000 IU or 50,000–500,000 IU), or got vitamin D 1000–10,000 IU daily, lasting for 30–60 days could achieve better pregnancy outcome. Conclusion To the best of our knowledge, this is the first meta-analysis systematically investigated that moderate daily dosing of vitamin D supplementation could improve the clinical pregnancy rate of infertile women and reported the effects of vitamin D supplementation parameters on pregnancy outcomes. A larger sample size and high-quality RCTs are necessary to optimize the parameters of vitamin D supplementation to help more infertile patients benefit from this therapy.

Background Polycystic ovary syndrome (PCOS) patients typically undergo either an ovulation induction regimen or a programmed regimen for endometrial preparation before frozen embryo transfer (FET). However, the superiority of one approach over the other remains controversial. While previous studies suggest that the letrozole regimen may improve pregnancy outcomes, prospective studies are insufficient. Therefore, we designed a multi-center randomized controlled trial to compare the pregnancy outcomes between these two regimens in PCOS patients undergoing FET. Methods This multicentre, randomised controlled, open-label trial included 155 PCOS patients from six hospitals in China between September 2022 and February 2024. Patients were randomised into either the letrozole ovulation regimen group ( n  = 81) or the programmed regimen group ( n  = 74) during FET cycles. Subgroup analysis was used among patients with single blastocyst transfer. The primary outcome was clinical pregnancy rate, with secondary outcomes including abortion rate, live birth rate, and other pregnancy and neonatal outcomes. Results Analysis of 155 FET women showed no significant difference in clinical pregnancy rates between the letrozole group (62.96%) and the programmed group (60.81%, P  > 0.05). Similarly, no differences were observed in abortion rate, live birth rate, hypertensive disorders of pregnancy, gestational diabetes mellitus, preterm birth, or neonatal birth weight. However, more patients in the letrozole group received single-drug luteal support (53.16% vs. 16.67%, P  < 0.05). A subgroup analysis of 108 women involving patients who underwent single blastocyst transfer revealed no significant differences in clinical pregnancy rates (66.67% vs. 73.33%, P  > 0.05) or live birth rates (58.73% vs. 55.56%, P  > 0.05) between the two groups. A higher proportion of women in the letrozole ovulation regimen group received single-drug luteal support compared to those in the programmed regimen group (58.73% vs. 22.22%, P  < 0.05). No statistically significant differences were observed between the groups in terms of fertilization method, abortion rate, or obstetric and neonatal outcomes. Conclusions The letrozole ovulation regimen demonstrated comparable clinical pregnancy rates to the programmed regimen in PCOS patients undergoing FET, while requiring only simple luteal support. These findings suggest that the letrozole regimen may be a favourable alternative for endometrial preparation in this population. Trial registration Chinese Clinical Trial Registry ChiCTR2200062244 ( https://www.chictr.org.cn ). Registered on 31 July 2022.

To improve the quality of in vitro produced (IVP) embryos and reduce pregnancy losses, we proposed to reduce the components of the synthetic oviduct fluid (SOF) medium by 0% (SOF100), 50% (SOF50), and 75% (SOF25). First, embryos produced under these three treatments were evaluated for production, quality, lipid content, gene expression, and methylation patterns. The results indicated that all parameters analyzed were similar across all treatments ( P  > 0.05), suggesting that reducing media components does not affect embryo development and quality. Subsequently, we selected SOF25 for comparison with SOF100 in a commercial laboratory setting, evaluating embryo production, response to cryopreservation, gestation rate, and offspring birth. The data demonstrated that a 75% reduction in SOF medium components did not affect embryo development, quality, pregnancy rate, embryonic losses between 30 and 60 days, or birth rate ( P  > 0.05). To our knowledge, this is the first report on the pregnancy and birth rates of bovine blastocysts produced in media with nutrient concentrations as low as 25%. These results introduce novel cultural conditions that can be immediately incorporated into the IVF routine.