[Analysis of typing conversion and perinatal outcomes in twins with selective intrauterine growth restriction of...

Objective: To retrospectively analyze the clinical data of different types of selective intrauterine growth restriction (sIUGR) pregnant women under expectant management, including the natural evolution, typing conversion and perinatal outcomes. Methods: The clinical data of 153 pregnant women with sIUGR under expected treatment in Women's Hospital, Zhejiang University School of Medicine from January 2014 to December 2018 were collected. Maternal characteristics including maternal age, gravidity, parity, method of conception, pregnancy complication, gestational age at delivery, indication for delivery, birth weight, the rate of intrauterine and neonatal death and neonatal outcomes were recorded. Pregnant women with sIUGR were divided into three types according to end-diastolic umbilical artery flow Doppler ultrasonography, and the differences of typing conversion and perinatal outcomes of sIUGR pregnant women based on the first diagnosis were compared. Results: (1) Clinical characteristics and pregnancy outcomes: among 153 pregnant women with sIUGR, 100 cases (65.3%) were diagnosed with type Ⅰ, 35 cases (22.9%) with type Ⅱ, and 18 cases (11.8%) with type Ⅲ. There were no significant differences in age, conception mode, pregnancy complications, first diagnosis gestational age, characteristics of umbilical cord insertion, delivery indications, fetal intrauterine mortality and neonatal mortality among three types of sIUGR pregnant women (all P>0.05). The average gestational age at delivery of type Ⅰ sIUGR was (33.5±1.9) weeks, which was significantly later than those of type Ⅱ and Ⅲ [(31.3±1.8), (31.2±1.1) weeks, P<0.001]. The percentage disordance in estimated fetal weight (EFW) of type Ⅰ sIUGR was significantly lower than those of type Ⅱ and type Ⅲ (P<0.001). The incidence rate of neonatal intensive care unit (NICU) admission, cerebral leukomalacia and respiratory complications of both fetus and necrotizing enterocolitis of large fetus in type Ⅰ were significantly lower than those in type Ⅱ and type Ⅲ (all P<0.05). (2) Typing conversion: in 100 cases of type Ⅰ sIUGR, 18 cases progressed to type Ⅱ and 10 cases progressed to type Ⅲ. Compared with 72 stable type Ⅰ sIUGR, those with progressed type Ⅰ sIUGR had higher incidence of NICU admission and lung disease in both fetuses, and cerebral leukomalacia and necrotizing enterocolitis in large fetus (all P<0.05). The proportion of inconsistent cord insertion was significantly higher in those type Ⅰ progressed to type Ⅲ (6/10) than in those with stable type Ⅰ (19.4%, 14/72) and type Ⅰ progressed to type Ⅱ sIUGR [0 (0/18), P=0.001]. Four cases of type Ⅱ sIUGR reversed to type Ⅰ and 6 cases reversed to type Ⅲ. Compared with type Ⅱ reversed to type Ⅰ sIUGR, those stable type Ⅱ and type Ⅱ reversed to type Ⅲ sIUGR had a higher incidence of NICU admission in large fetus (P<0.05). Two cases of type Ⅲ sIUGR reversed to type Ⅰ and 6 cases progressed to type Ⅱ. There were no significant differences in fetal serious complications in type Ⅲ sIUGR with or without doppler changes (all P>0.05). Conclusions: The different types of sIUGR could convert to each other. The frequency of ultrasound examinations should be increased for patients with the type Ⅰ sIUGR, especially when the percentage discordance in EFW is substantial or with discordant cord insersion.