Abstract
ObjectiveTo evaluate the risk factors for different types of pregnancy losses after embryo transfer (ET).DesignRetrospective cohort study.SettingReproductive medicine center.ParticipantsA total of 15,210 pregnancies after fresh and frozen-thawed embryo transfer between January 2014 and June 2019.Main Outcome MeasuresThe primary outcome was pregnancy loss (PL) throughout the entire pregnancy. Secondary outcomes were non-visualized PL, early miscarriage, late miscarriage, and stillbirth.MethodsThe effect of patients’ baseline characteristics and IVF/ICSI cycle-specific factors on the risk of PL after fresh and frozen-thawed ET was determined by multivariate logistic regression analysis.ResultsCompared to women under 35 years old, those between 35 and 40 had an increased risk of early miscarriage [odds ratio (OR) 1.49, 95% confidence interval (CI) 1.22-1.83], while those after 40 appeared to have an increased risk of both early miscarriage (OR 3.82, 95% CI 2.65-5.51) and late miscarriage (OR 2.79, 95% CI 1.64-4.77). Overweight patients were observed to have a higher risk of late miscarriage (OR 1.38, 95% CI 1.16-1.65), while obese patients showed a higher risk of both early miscarriage (OR 1.47, 95% CI 1.14-1.91) and late miscarriage (OR 1.80, 95% CI 1.33-2.44). Polycystic ovary syndrome (PCOS) was an independent risk factor for late miscarriage (OR 1.58, 95% CI 1.28-1.96), and the detrimental effect of PCOS was independent of obesity status. Women with uterine factors had a higher risk of early miscarriage (OR 1.77 (95% CI 1.32-2.38) than women without uterine factors. A negative correlation was observed between the thickness of the endometrium and PL (OR 0.95 95% CI 0.92-0.97). There was an increased risk of PL after frozen-thawed ET versus fresh ET (OR 1.12, 95% CI 1.01-1.24). Women who transferred ≥2 embryos showed lower risk of overall PL than women who transferred a single embryo, with adjusted ORs ranged from 0.57~0.94. However, women who transferred three embryos demonstrated a higher risk of late miscarriage than women who transferred a single embryo (OR 2.23, 95% CI 1.36-3.66).ConclusionsPatients with uterine factors demonstrated higher risk of early miscarriage and stillbirth. Being overweight, PCOS, and transferring three embryos was associated with late miscarriage. Being aged 40 and over, obese, and using frozen embryo transfer was associated with early and late miscarriage.
Highlights
Nowadays, assisted reproductive technology (ART) has become a common technique for infertility treatment worldwide
There were 1,746 (11.48%) patients diagnosed with Polycystic ovary syndrome (PCOS), 6,550 (43.15%) patients diagnosed with male factors, and 667 (5.17%) with uterine factors
We found that PCOS was an independent risk factor for late miscarriage, but not for nonvisualized Pregnancy loss (PL), early miscarriage, and stillbirth after adjusting for confounding variables (Table 4)
Summary
Nowadays, assisted reproductive technology (ART) has become a common technique for infertility treatment worldwide. The clinical pregnancy rate has gradually improved over the past decades, the live birth rate is still low, only 38.1% [1]. Pregnancy loss (PL) is the spontaneous demise of an embryo throughout the entire pregnancy [2]. It includes non-visualized PL and clinical pregnancy losses [3]. Studies on patients conceiving through ART showed that they were confronted with even more of a probability of PL than naturally conceiving women [1, 4, 5]. It is of great significance to estimate the risk factors for PL in order to assess the overall effectiveness of in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) and improve patient counselling before the initiation of treatments
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