OBJECTIVE: To compare the effectiveness and safety of 1 cycle of assisted reproductive technology (ART) vs. 3 cycles of intrauterine insemination (IUI). DESIGN: Target trial emulation using observational data. SETTING: A healthcare claims database (2011-2015). PATIENT(S): The patients were 29,021 women aged 18-45 years with an infertility diagnosis and no history of IUI or ART within the past 12 months. INTERVENTION(S): One ART cycle immediately, with no more cycles of ART or IUI within the next 4 months; or 1 IUI cycle immediately, with 2 additional consecutive cycles of IUI within the next 4 months unless pregnancy occurred. MAIN OUTCOME MEASURE(S): Live births, multiple births, congenital malformations, preterm births, small-for-gestational-age newborns, large-for-gestational-age newborns, admission to neonatal intensive care unit (NICU), gestational diabetes, preeclampsia, and gestational hypertension. RESULT(S): The probability of live birth was 27.3% for ART and 26.3% for IUI. The observational analogue of per-protocol risk difference (95% confidence interval) for ART compared with IUI was 1.0% (-0.1%, 2.2%) for live births, 4.3% (3.7%, 4.9%) for multiple births, 3.4% (2.8%, 4.0%) for preterm births, 1.5% (0.9%, 2.1%) for NICU admissions, and 0.6% (0.2%, 1.0%) for gestational diabetes. The risk differences for the other outcomes were <0.5%. The results of the 2 strategies were similar in women ≤40 years, but in women >40 years the probability of live birth was greater for ART (14.4%) than for IUI (7.4%). CONCLUSION(S): Compared with 3 cycles of IUI, 1 cycle of ART was estimated to have a similar probability of live birth but slightly higher risks of multiple gestations, preterm births, and NICU admissions.

Retroviral infections of the germline have the potential to episodically alter gene function and genome structure during the course of evolution. Horizontal transmissions between species have been proposed, but little evidence exists for such events in the human/great ape lineage of evolution. Based on analysis of finished BAC chimpanzee genome sequence, we characterize a retroviral element (Pan troglodytes endogenous retrovirus 1 [PTERV1]) that has become integrated in the germline of African great ape and Old World monkey species but is absent from humans and Asian ape genomes. We unambiguously map 287 retroviral integration sites and determine that approximately 95.8% of the insertions occur at non-orthologous regions between closely related species. Phylogenetic analysis of the endogenous retrovirus reveals that the gorilla and chimpanzee elements share a monophyletic origin with a subset of the Old World monkey retroviral elements, but that the average sequence divergence exceeds neutral expectation for a strictly nuclear inherited DNA molecule. Within the chimpanzee, there is a significant integration bias against genes, with only 14 of these insertions mapping within intronic regions. Six out of ten of these genes, for which there are expression data, show significant differences in transcript expression between human and chimpanzee. Our data are consistent with a retroviral infection that bombarded the genomes of chimpanzees and gorillas independently and concurrently, 3-4 million years ago. We speculate on the potential impact of such recent events on the evolution of humans and great apes.