Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Lis Hospital for Women, Sourasky Medical Center and Sackler Faculty of Medicine, Tel-Aviv University, Israel.
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
Am J Obstet Gynecol. 2021 Aug;225(2):187.e1-187.e14. doi: 10.1016/j.ajog.2021.01.018. Epub 2021 Jan 25.
Intertwin size discordance is an independent risk factor for adverse neonatal outcomes in twin pregnancies. However, size discordance at a given point in gestation fails to take into consideration information, such as the timing of onset and the rate of progression of discordance, that may be of prognostic value.
In this study, we aimed to identify distinct patterns of discordant fetal growth in twin pregnancies and to determine whether these patterns are predictive of adverse pregnancy outcomes.
This was a retrospective cohort study of women with twin pregnancies in a single tertiary referral center between January 2011 and April 2020, who had at least 3 ultrasound examinations during pregnancy that included assessment of fetal biometry. Size discordance was calculated at each ultrasound examination, and pregnancies were classified into 1 of 4 predetermined patterns based on the timing of onset and the progression of discordance: pattern 1, no significant discordance group (referent); pattern 2, early (<24 weeks' gestation) progressive discordance group; pattern 3, early discordance with plateau group; or pattern 4, late (≥24 weeks' gestation) discordance group. The associations of discordance pattern (using pattern 1 as referent) with preterm birth, preeclampsia, size discordance at birth, and birthweight<10th percentile were expressed as adjusted relative risk with 95% confidence intervals and were compared with those observed for a single measurement of size discordance at 32 weeks' gestation.
Of 2075 women with a twin gestation who were identified during the study period, 1059 met the study criteria. Of the 1059 women, 599 (57%) were classified as no significant discordance (pattern 1), 23 (2%) as early progressive discordance (pattern 2), 160 (15%) as early discordance with plateau (pattern 3), and 277 (26%) as late discordance (pattern 4). The associations of discordance pattern with preterm birth at <34 weeks' gestation and preeclampsia were strongest for pattern 2 (rates of 43% [adjusted relative risk, 3.43; 95% confidence interval, 2.10-5.62] and 17% [adjusted relative risk, 5.81; 95% confidence interval, 2.31-14.60], respectively), intermediate for pattern 3 (rates of 23% [adjusted relative risk, 1.82; 95% confidence interval, 1.28-2.59] and 6% [adjusted relative risk, 2.08; 95% confidence interval, 1.01-4.43], respectively), and weakest for pattern 4 (rates of 12% [adjusted relative risk, 0.96; 95% confidence interval, 0.65-1.42] and 4% [adjusted relative risk, 1.41; 0.68-2.92], respectively). In contrast, a single measurement of size discordance at 32 weeks' gestation showed no association with preeclampsia and only a weak association with preterm birth at <34 weeks' gestation.
We identified 4 distinct discordance growth patterns among twins that demonstrated a dose-response relationship with adverse outcomes and seemed to be more informative than a single measurement of size discordance.
双胎妊娠中，胎儿大小的不一致是不良新生儿结局的独立危险因素。然而，在特定的妊娠阶段进行大小不一致的评估并不能考虑到一些可能具有预后价值的信息，如不一致的起始时间和进展速度。
本研究旨在识别双胎妊娠中不同的胎儿生长不一致模式，并确定这些模式是否可预测不良妊娠结局。
这是一项在单中心回顾性队列研究，纳入了 2011 年 1 月至 2020 年 4 月期间在一家三级转诊中心就诊的双胎妊娠妇女，这些妇女在妊娠期间至少进行了 3 次超声检查，包括胎儿生物测量评估。在每次超声检查时计算胎儿大小不一致的程度，并根据不一致的起始时间和进展速度将妊娠分为 4 种预先设定的模式之一：模式 1，无明显不一致（参考组）；模式 2，<24 周时出现的渐进性不一致；模式 3，24 周前出现的不一致并伴有平台期；或模式 4，≥24 周时出现的不一致。不一致模式（以模式 1 为参考）与早产、子痫前期、出生时的大小不一致以及出生体重<第 10 百分位的关联，用调整后的相对风险（95%置信区间）表示，并与 32 周时单次测量的大小不一致进行比较。
在研究期间确定的 2075 例双胎妊娠妇女中，有 1059 例符合研究标准。在这 1059 名妇女中，599 名（57%）被归类为无明显不一致（模式 1），23 名（2%）为早期渐进性不一致（模式 2），160 名（15%）为早期不一致伴有平台期（模式 3），277 名（26%）为晚期不一致（模式 4）。不一致模式与早产（<34 周）和子痫前期的关联在模式 2 中最强（早产发生率分别为 43%[调整后的相对风险，3.43；95%置信区间，2.10-5.62]和 17%[调整后的相对风险，5.81；95%置信区间，2.31-14.60]），在模式 3 中为中等程度（早产发生率分别为 23%[调整后的相对风险，1.82；95%置信区间，1.28-2.59]和 6%[调整后的相对风险，2.08；95%置信区间，1.01-4.43]），在模式 4 中最弱（早产发生率分别为 12%[调整后的相对风险，0.96；95%置信区间，0.65-1.42]和 4%[调整后的相对风险，1.41；95%置信区间，0.68-2.92]）。相比之下，32 周时单次测量的大小不一致与子痫前期无关联，与<34 周时的早产仅存在微弱关联。
我们在双胎妊娠中发现了 4 种不同的胎儿生长不一致模式，这些模式与不良结局呈剂量反应关系，似乎比单次测量的大小不一致更具信息价值。
