Association between endometrial thickness and neonatal outcomes in intrauterine insemination cycles: a retrospective analysis of 1,016 live-born singletons.
BACKGROUND
Decreased endometrial thickness (EMT) has been suggested to be associated with reduced birthweight of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) newborns. Considering the differences in ovarian stimulation degree and laboratory procedures between IVF/ICSI and IUI treatment, we aim to investigate whether EMT has any influence on IUI infant outcomes as well.


METHODS
This was a retrospective cohort study of 1016 patients who had singleton livebirths after IUI treatment cycles from January 2008 to December 2018 at a tertiary-care academic medical center in China. Patients were categorized into three groups by the 10th and 90th percentile of peak EMT: ≤7.6, 7.7-13.0 and ≥ 13.1 mm. The primary outcomes of the study were preterm birth (PTB), low birthweight (LBW) and small-for-gestational age (SGA). Multiple regression analyses were performed after controlling for a variety of potential confounders.


RESULTS
No significant differences were found among the three groups in gestational age, birthweight and birthweight Z-score. Compared with the EMT 7.7-13.0 mm group, the incidences of PTB, LBW and SGA were 5.5% (adjusted odds ratio [aOR] 0.81, 95% confidence interval [CI] 0.33-2.01), 6.4% (aOR 1.44, 95% CI 0.58-3.58) and 7.3% (aOR 1.21, 95% CI 0.53-2.76) in the EMT ≤7.6 mm group, respectively. Similarly, EMT ≥13.1 mm was not significantly associated with risks of PTB (aOR 0.63, 95% CI 0.24-1.65), LBW (aOR 0.57, 95% CI 0.17-1.95) and SGA (aOR 0.73, 95% CI 0.28-1.92). The odds of other adverse neonatal outcomes, including macrosomia, large-for-gestational age and major congenital malformations, did not show significant differences before and after adjustment in both EMT ≤7.6 and ≥ 13.1 mm groups.


CONCLUSIONS
EMT is not independently associated with adverse perinatal outcomes in IUI cycles. This novel finding would provide reassuring information for IUI patients with thin endometrial linings regarding their neonatal health. However, further prospective cohort studies with larger datasets are needed to confirm the conclusion.
['Huang|Jialyu|J|', 'Lin|Jiaying|J|', 'Lu|Xuefeng|X|', 'Gao|Hongyuan|H|', 'Song|Ning|N|', 'Cai|Renfei|R|', 'Kuang|Yanping|Y|']
D000328:Adult D001724:Birth Weight D002681:China D015331:Cohort Studies D004717:Endometrium D005260:Female D006801:Humans D007231:Infant, Newborn D007232:Infant, Newborn, Diseases D007246:Infertility D050498:Live Birth D008297:Male D009929:Organ Size D011247:Pregnancy D011256:Pregnancy Outcome D011379:Prognosis D012189:Retrospective Studies D012307:Risk Factors D020554:Sperm Injections, Intracytoplasmic D016896:Treatment Outcome
Endometrial thickness Neonatal outcomes Intrauterine insemination Birthweight Gestational age