Hackmon Rinat, Librach Clifford, Burwick Richard, Rodrigues Nicole, Farine Dan, Berger Howard
Maternal Fetal Medicine Unit, Saint Michael's Hospital, Toronto, ON; Maternal Fetal Medicine Unit, Mount Sinai Hospital, Toronto, ON; Maternal Fetal Medicine Division, Obstetrics and Gynecology, School of Medicine, Oregon Health and Science University, Portland, OR.
Family Medicine Obstetrics, Sunnybrook Health Sciences Centre, Toronto, ON; Gynecology Program, Women's College Hospital, Toronto, ON; Create Fertility Centre, Toronto, ON.
J Obstet Gynaecol Can. 2017 Sep;39(9):750-756. doi: 10.1016/j.jogc.2017.04.034. Epub 2017 Jul 18.
Traditionally, physiological variation in fetal weight is believed to emerge during the latter half of pregnancy. Although recent evidence suggests that crown-rump length (CRL) and nuchal translucency (NT) measured at 11-14 weeks correlate with abnormal fetal growth, findings have been limited by dating accuracy in spontaneous gestations. Therefore, we sought to determine whether CRL or NT measurements correlated with term birth weight (BW) or BW ratio in a cohort of IVF pregnancies, in which the date of conception is precisely known.
This retrospective cohort study included 227 term, singleton IVF pregnancies. Subjects were included if they had an early first-trimester ultrasound examination and subsequent nuchal translucency (NT) screening. The difference between the measured and the expected CRL and the biparietal diameter (BPD) and NT measurement were calculated and correlated with the actual term BW or BW ratio. The BW ratio was calculated using the actual BW and the expected BW for GA.
The difference between measured and expected mid-first-trimester CRL, and the BPD at NT assessment, correlated with BW ratio at delivery (r = 0.15, P = 0.023 and r = 0.27, P < 0.001, respectively). Absolute NT measurements and NT percentiles (adjusted for CRL) correlated with BW ratio at delivery (r = 0.18, r = 0.14, and P = 0.005 and 0.038, respectively).
In this well-dated IVF population, we report a significant correlation between BW ratio and first-trimester CRL, BPD, and NT measurements. These findings support the hypothesis that physiological variation in BW can be reflected by variation in first-trimester fetal measurements.
传统观点认为，胎儿体重的生理变化在妊娠后半期出现。尽管最近有证据表明，孕11 - 14周时测量的头臀长（CRL）和颈项透明层（NT）与胎儿生长异常相关，但在自然妊娠中，这些发现受到孕周确定准确性的限制。因此，我们试图确定在一批体外受精（IVF）妊娠中，CRL或NT测量值是否与足月出生体重（BW）或BW比值相关，在这类妊娠中，受孕日期是确切已知的。
这项回顾性队列研究纳入了227例足月单胎IVF妊娠。如果受试者在孕早期进行了首次超声检查并随后进行了颈项透明层（NT）筛查，则纳入研究。计算测量的CRL与预期CRL之间的差异、双顶径（BPD）以及NT测量值，并将其与实际足月BW或BW比值进行相关性分析。BW比值通过实际BW与根据孕周预期的BW计算得出。
孕早期测量的CRL与预期CRL之间的差异以及NT评估时的BPD与分娩时的BW比值相关（r分别为0.15，P = 0.023和r = 0.27，P < 0.001）。绝对NT测量值和NT百分位数（根据CRL进行调整）与分娩时的BW比值相关（r分别为0.18，r = 0.14，P分别为0.005和0.038）。
在这个孕周确定准确的IVF人群中，我们报告了BW比值与孕早期CRL、BPD和NT测量值之间存在显著相关性。这些发现支持了以下假设，即BW的生理变化可以通过孕早期胎儿测量值的变化来反映。
