IVIRMA.
IVI Foundation, Health Research Institute La Fe.
Curr Opin Obstet Gynecol. 2022 Jun 1;34(3):114-121. doi: 10.1097/GCO.0000000000000778.
To summarize recent findings related to the risk of miscarriage in women with elevated BMI undergoing IVF, and the mechanisms involved in said risk.
Miscarriage rates are increased in overweight and obese women in both natural and assisted reproduction. Oocyte and embryo quality assessed according to classic morphological static parameters does not seem to be affected by excessive female body weight. Despite the initial lack of consensus between studies regarding embryo morphokinetics in obese women, blastocyst formation and quality have recently been shown to be similar across BMI groups, even in the case of euploid embryos. However, some metabolomic differences have been described in oocytes and embryos from obese women, thus pointing to a functional alteration. In women with elevated BMI, the percentage of aneuploid embryos is similar to that of normal weight women, and rates of miscarriage are higher, despite the transfer of euploid embryos. Therefore, the origin of the increased pregnancy loss rate after IVF in these women may be related to metabolomic, epigenetic or mitochondrial oocyte and embryo disturbances, or to the abnormal endocrine, metabolic and inflammatory uterine environment induced by obesity, which seems to be also responsible for other numerous complications during pregnancy and the in-utero fetal programming of postnatal diseases. A displacement of the window of implantation in obese women undergoing artificial endometrial preparation has recently been described and may be related to the poorer embryo implantation rates and increased risk of miscarriage observed following fresh and frozen embryo transfers with autologous oocytes, and with donated ova in recipients with extremely high BMI.
Female obesity is related to poorer outcome in natural and assisted conception, including an increased risk of miscarriage. Embryo morphology, assessed by conventional methods or by morphokinetics, does not seem to be affected by excess weight, with similar blastocyst formation and quality than normal weight women reported in IVF cycles. Embryo aneuploidy is not increased, and higher miscarriages rates are seen after euploid embryo transfer in obese women. Disturbances of the uterus or its environment induced by female obesity seem to be the most likely cause of the increased risk of miscarriage, although metabolomic, epigenetic or mitochondrial oocyte and embryo dysfunction cannot be ruled out as cannot congenital anomalies. In the context of all the above, weight reduction before pregnancy should be advised in obese women trying to become pregnant.
超重和肥胖女性在接受 IVF 时发生流产的风险及相关机制。
自然妊娠和辅助生殖中，超重和肥胖女性的流产率增加。根据经典的形态学静态参数评估的卵母细胞和胚胎质量似乎不受女性体重过度增加的影响。尽管肥胖女性胚胎形态动力学的初始研究结果缺乏一致性，但最近的研究表明，囊胚形成和质量在 BMI 组之间相似，即使是整倍体胚胎也是如此。然而，已经在肥胖女性的卵母细胞和胚胎中描述了一些代谢组学差异，因此指向功能改变。在 BMI 升高的女性中，与正常体重女性相比，非整倍体胚胎的比例相似，但流产率更高，尽管移植了整倍体胚胎。因此，这些女性在接受 IVF 后妊娠丢失率增加的原因可能与卵母细胞和胚胎的代谢组学、表观遗传学或线粒体功能障碍有关，也可能与肥胖引起的异常内分泌、代谢和炎症子宫环境有关，这似乎也是导致妊娠期间和宫内胎儿编程中发生多种疾病的原因。最近描述了肥胖女性在进行人工子宫内膜准备时着床窗口的偏移，这可能与以下情况有关：接受自体卵母细胞或供体卵的新鲜和冷冻胚胎移植后观察到的胚胎着床率较差和流产风险增加，在 BMI 极高的受者中也是如此。
女性肥胖与自然和辅助妊娠的不良结局相关，包括流产风险增加。通过传统方法或形态动力学评估的胚胎形态似乎不受体重增加的影响，与正常体重女性相比，IVF 周期中报道的囊胚形成和质量相似。胚胎非整倍体率没有增加，肥胖女性在移植整倍体胚胎后流产率更高。女性肥胖引起的子宫或其环境的紊乱似乎是流产风险增加的最可能原因，尽管不能排除卵母细胞和胚胎的代谢组学、表观遗传学或线粒体功能障碍以及先天性异常。在上述所有情况下，建议肥胖女性在备孕前减轻体重。
