Table_1_Fetal Reduction Could Improve but Not Completely Reverse the Pregnancy Outcomes of Multiple Pregnancies: Experience From a Single Center.docx

ObjectiveTo investigate the effectiveness and limitations of multifetal pregnancy reduction (MFPR) on the improvement of pregnancy outcomes of triplet or twin pregnancies conceived by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).
MethodsWe performed a cohort study of women undergoing IVF or ICSI from 2002–2016 in reproductive center, women’s hospital, Zhejiang University School of Medicine. The cohort included 502 women who underwent MFPR and 9641 non-reduced women. Pregnancy outcomes were gestational age (GA) at delivery, pregnancy loss, preterm delivery, low birth weight (LBW), very low birth weight (VLBW), and small for gestational age (SGA). Multiple linear regression and logistic regression models were used to compare pregnancy outcomes between groups.
ResultsTriplets reduced to singletons had a longer median GA (39.07 vs 37.00, P<0.001), and lower rates of LBW (8.9% vs 53.2%, P<0.001) and SGA (17.8% vs 44.7%, P=0.001) than triplets reduced to twins, with a similar pregnancy loss rate (6.7% vs 6.6%, P=0.701). Twins reduced to singletons had a comparable pregnancy loss rate (4.8% vs. 6.5%, P=0.40), a longer median GA (38.79 vs. 37.00, P<0.001), and lower rates of LBW (13.5% vs. 47.0%, P<0.001) and SGA (13.5% vs. 39.6%, P<0.001) than primary twins. Triplets reduced to twins had higher rates of LBW (53.2% vs. 47.0%, P=0.028) and SGA (44.7% vs. 39.6%, P=0.040) than primary twins, with a similar pregnancy loss rate (6.6% vs. 6.5%, P=0.877). Singletons reduced from triplets/twins had higher rates of preterm delivery (15.8% vs. 7.3%, P<0.001), LBW (12.3% vs. 4.32%, P<0.001), VLBW (2.3% vs. 0.4%, P=0.002), and SGA (14.6% vs.6.6%, P<0.001) than primary singletons, with a comparable pregnancy loss rate (5.3% vs. 5.4%, P=0.671).
ConclusionsThis study suggests that the pregnancy loss rate is similar between reduction and non-reduction groups. MFPR improves pregnancy outcomes, including the risk of preterm delivery, LBW, and SGA, but still could not completely reverse the adverse pregnancy outcomes of multiple pregnancies.

研究目的：探讨多胎妊娠减胎术（multifetal pregnancy reduction, MFPR）对体外受精（in vitro fertilization, IVF）或卵胞浆内单精子注射（intracytoplasmic sperm injection, ICSI）术后双胎、三胎妊娠的妊娠结局的改善效果与局限性。
方法：本研究为队列研究，研究对象为2002年至2016年于浙江大学医学院附属妇产科医院生殖中心接受IVF或ICSI治疗的女性。本队列共纳入502例行MFPR的女性与9641例未行减胎术的女性。妊娠结局指标包括分娩时孕周（gestational age, GA）、妊娠丢失、早产、低出生体重（low birth weight, LBW）、极低出生体重（very low birth weight, VLBW）以及小于胎龄儿（small for gestational age, SGA）。本研究采用多重线性回归与logistic回归模型对比两组的妊娠结局。
结果：相较于减至双胎的三胎妊娠，减至单胎的三胎妊娠的中位孕周更长（39.07 vs 37.00，P<0.001），低出生体重（LBW）发生率（8.9% vs 53.2%，P<0.001）与小于胎龄儿（SGA）发生率（17.8% vs 44.7%，P=0.001）更低，二者妊娠丢失率相近（6.7% vs 6.6%，P=0.701）。相较于原发性双胎妊娠，减至单胎的双胎妊娠妊娠丢失率相当（4.8% vs 6.5%，P=0.40），中位孕周更长（38.79 vs 37.00，P<0.001），LBW发生率（13.5% vs 47.0%，P<0.001）与SGA发生率（13.5% vs 39.6%，P<0.001）更低。相较于原发性双胎妊娠，减至双胎的三胎妊娠LBW发生率（53.2% vs 47.0%，P=0.028）与SGA发生率（44.7% vs 39.6%，P=0.040）更高，二者妊娠丢失率相近（6.6% vs 6.5%，P=0.877）。相较于原发性单胎妊娠，由三胎/双胎减至的单胎妊娠早产发生率（15.8% vs 7.3%，P<0.001）、LBW发生率（12.3% vs 4.32%，P<0.001）、极低出生体重儿（VLBW）发生率（2.3% vs 0.4%，P=0.002）以及SGA发生率（14.6% vs 6.6%，P<0.001）均更高，二者妊娠丢失率相当（5.3% vs 5.4%，P=0.671）。
结论：本研究表明，减胎组与非减胎组的妊娠丢失率无显著差异。MFPR可改善早产、LBW以及SGA相关的妊娠结局风险，但仍无法完全逆转多胎妊娠的不良妊娠结局。