Abstract：
OBJECTIVE: What is the association between endometrial thickness (EMT) and the birthweight of singleton infants born from frozen-thawed embryo transfer cycles?
METHODS: This retrospective cohort study was conducted from January 2016 to December 2019. Participants were categorized into a natural cycle (NC, n = 8132) group and hormone replacement therapy (HRT, n = 4975) group. Only singleton deliveries were included. The primary outcomes were measures of birthweight and relevant indexes. Multivariable logistic regression and multivariable-adjusted linear regression models that incorporated restricted cubic splines were used.
RESULTS: In the HRT group, the risk of delivering a small for gestational age (SGA) infant was increased in women with an EMT <8.0 mm (adjusted odds ratio [aOR] 1.85, 95% confidence interval [CI] 1.17-2.91) compared with women with an EMT of 8.0 to <12.0 mm, and increased with an EMT ≥12.0 mm (aOR 1.85, 95% CI 1.03-3.33). An inverted U-shaped relationship was found between EMT and birthweight in women with HRT. No significant differences were shown in birthweight z-score, or being SGA or large for gestational age, in singletons among the three EMT groups in the natural cycles.
CONCLUSIONS: A thinner endometrium seen in women undergoing HRT cycles was associated with a lower birthweight z-score, as well as a higher risk of SGA. However, no significant association was observed between EMT and birthweight z-score or SGA in the NC group. It is noteworthy that a thicker endometrium was not associated with a higher birthweight in frozen-thawed embryo transfer (FET) cycles. Women with a thin endometrium who achieve pregnancy require specialized attention, particularly if they are undergoing FET with HRT cycles.
METHODS: This retrospective cohort study was conducted from January 2016 to December 2019. Participants were categorized into a natural cycle (NC, n = 8132) group and hormone replacement therapy (HRT, n = 4975) group. Only singleton deliveries were included. The primary outcomes were measures of birthweight and relevant indexes. Multivariable logistic regression and multivariable-adjusted linear regression models that incorporated restricted cubic splines were used.
RESULTS: In the HRT group, the risk of delivering a small for gestational age (SGA) infant was increased in women with an EMT <8.0 mm (adjusted odds ratio [aOR] 1.85, 95% confidence interval [CI] 1.17-2.91) compared with women with an EMT of 8.0 to <12.0 mm, and increased with an EMT ≥12.0 mm (aOR 1.85, 95% CI 1.03-3.33). An inverted U-shaped relationship was found between EMT and birthweight in women with HRT. No significant differences were shown in birthweight z-score, or being SGA or large for gestational age, in singletons among the three EMT groups in the natural cycles.
CONCLUSIONS: A thinner endometrium seen in women undergoing HRT cycles was associated with a lower birthweight z-score, as well as a higher risk of SGA. However, no significant association was observed between EMT and birthweight z-score or SGA in the NC group. It is noteworthy that a thicker endometrium was not associated with a higher birthweight in frozen-thawed embryo transfer (FET) cycles. Women with a thin endometrium who achieve pregnancy require specialized attention, particularly if they are undergoing FET with HRT cycles.
摘要：
目的：子宫内膜厚度（EMT）与冻融胚胎移植周期出生的单胎婴儿的出生体重之间有什么关系？
方法：这项回顾性队列研究于2016年1月至2019年12月进行。参与者被归类为自然周期(NC，n=8132）组和激素替代疗法（HRT，n=4975)组。仅包括单例交付。主要结果是测量出生体重和相关指标。使用了包含受限三次样条的多变量逻辑回归和多变量调整线性回归模型。
结果：在HRT组中，与EMT为8.0至<12.0mm的女性相比，EMT<8.0mm的女性分娩小于胎龄（SGA）婴儿的风险增加（调整后比值比[aOR]1.85，95％置信区间[CI]1.17-2.91），并随EMT≥12.0mm而增加(aOR1.85，95%CI1.03-3.33)。在患有HRT的女性中，EMT与出生体重之间存在倒U形关系。出生体重z评分没有显着差异，或者是SGA或胎龄较大，在自然周期中三个EMT组中的单身人士中。
结论：在接受HRT周期的女性中，子宫内膜变薄与较低的出生体重z评分相关，以及SGA的高风险。然而,在NC组中,EMT与出生体重z评分或SGA之间没有显著关联.值得注意的是，在冻融胚胎移植（FET）周期中，较厚的子宫内膜与较高的出生体重无关。子宫内膜薄且怀孕的女性需要特别注意，特别是如果他们正在经历FET与HRT周期。
方法：这项回顾性队列研究于2016年1月至2019年12月进行。参与者被归类为自然周期(NC，n=8132）组和激素替代疗法（HRT，n=4975)组。仅包括单例交付。主要结果是测量出生体重和相关指标。使用了包含受限三次样条的多变量逻辑回归和多变量调整线性回归模型。
结果：在HRT组中，与EMT为8.0至<12.0mm的女性相比，EMT<8.0mm的女性分娩小于胎龄（SGA）婴儿的风险增加（调整后比值比[aOR]1.85，95％置信区间[CI]1.17-2.91），并随EMT≥12.0mm而增加(aOR1.85，95%CI1.03-3.33)。在患有HRT的女性中，EMT与出生体重之间存在倒U形关系。出生体重z评分没有显着差异，或者是SGA或胎龄较大，在自然周期中三个EMT组中的单身人士中。
结论：在接受HRT周期的女性中，子宫内膜变薄与较低的出生体重z评分相关，以及SGA的高风险。然而,在NC组中,EMT与出生体重z评分或SGA之间没有显著关联.值得注意的是，在冻融胚胎移植（FET）周期中，较厚的子宫内膜与较高的出生体重无关。子宫内膜薄且怀孕的女性需要特别注意，特别是如果他们正在经历FET与HRT周期。
