Evaluating antenatal risk in twin pregnancies-A feasibility study to identify modifiable factors associated with adverse pregnancy outcomes.

INTRODUCTION: Twin pregnancies have significantly higher rates of perinatal morbidity and mortality compared to singleton pregnancies; current attempts to reduce perinatal mortality have been less successful in twin pregnancies. The paucity of information about modifiable risk factors for adverse neonatal outcomes in twin pregnancies, as well as independent effects of chorionicity may have contributed to this outcome. This study aimed to explore the feasibility of an observational study to identify modifiable factors associated with adverse neonatal outcomes in twin pregnancies. MATERIAL AND METHODS: Patients pregnant with twins at six UK hospitals between December 2019-March 2021 completed researcher-administered questionnaires at approximately 20-, 28- and 36-weeks' gestation, recording a wide range of self-reported social, lifestyle and demographic factors, alongside prospectively recorded clinical data from maternity records. Descriptive statistics were used to describe frequencies of exposures; logistic regression was used to determine whether factors were associated with a composite measure of adverse neonatal outcome. RESULTS: Data were collected from 65% (181/277) of eligible participants. A total of 98% (175) of participants had positive views about their participation. Some exposures, including cigarette smoking, supine sleep position and reduced fetal movements were less frequent in twin pregnancies compared to singletons, whereas fertility treatment was more common. Furthermore, different patterns of exposure were seen between monochorionic and dichorionic twins. This pilot study found some associations with adverse neonatal outcomes including: low BMI (OR 8.36, 95% CI: 1.02-68.87), maternal age ≥41 years (OR 9.0 95% CI: 1.07-75.84), maternally perceived high-stress levels (OR 1.96, 95% CI: 1.03-3.75) and inadequate antenatal screening (OR 1.44, 95% CI: 1.01-2.06). Sleep duration ≥9 h and right-sided going to sleep position were more frequent among pregnancies with adverse outcomes. Participants who reported receiving no information on fetal movement and reduced maternal perception of movements were more likely to have an adverse outcome, but sample size prohibited analysis based upon chorionicity. CONCLUSIONS: An observational study of modifiable factors in twin pregnancy is feasible. Differences in the frequencies of exposures between twin and singleton pregnancies highlight the need for twin-specific studies to identify modifiable factors and develop preventative strategies for morbidity and mortality in twin pregnancies.

Risk factors for adverse outcomes in twin pregnancies: a narrative review.

PURPOSE: Globally, the incidence of twin pregnancies is rising owing to the use of assisted reproductive technologies (ART), emigration and deferment of pregnancy until advanced maternal age (AMA). While twin pregnancies have higher absolute risks of adverse outcomes, including miscarriage, stillbirth, neonatal death and preterm delivery, the impact of specific exposures and risk factors related to these outcomes may differ between twin pregnancies and singleton pregnancies. Regarding modifiable factors, data are sometimes based on evidence extrapolated from singleton or whole obstetric populations. Therefore, targeted evidence is required to provide care tailored to twin pregnancies to prevent adverse outcomes. We aimed to comprehensively review the association between different risk factors and adverse outcomes in twin pregnancies, including data on chorionicity, and to compare these to singletons. MATERIALS AND METHODS: This review examines the risks associated with chorionicity, AMA, body mass index (BMI), socioeconomic and ethnic inequalities, maternal smoking, use of ART, maternal perception of fetal movement, and maternal comorbidities, including hypertensive disorders of pregnancy (HDP) and gestational diabetes mellitus (GDM). Adverse outcomes reported were preterm birth, admission to the neonatal intensive care unit (NICU), stillbirth and neonatal mortality. As such, fetal mortality and morbidity will be under-represented, as pregnancy loss before 22-24 weeks is omitted. RESULTS: Monochorionicity increases the risk of stillbirth, NICU admission, and preterm delivery in twin pregnancy. AMA predisposes twin pregnancies to higher risks of mortality, admission to the NICU, and preterm birth than singleton pregnancies do. Conversely, the impact of BMI, socioeconomic inequalities, smoking, ART, and HDP on adverse outcomes appears to be lower in twin pregnancies than in singleton pregnancies. This attenuation might be explained by the higher baseline risk of adverse outcomes such as preterm birth in twin pregnancies. Some exposures, such as ART use and GDM, appear to be "protective" against perinatal mortality in twin pregnancies, despite being established risk factors for adverse outcomes in singleton pregnancies, potentially related to access to specialist care. There is a paucity of evidence available to counsel mothers of twin pregnancies regarding reduced fetal movement. CONCLUSIONS: Overall, the risk factors for adverse pregnancy outcomes differ between twin and singleton pregnancies. This highlights the need for further studies to examine the association between risk factors and adverse outcomes in twin pregnancies. The resulting data would facilitate tailored guidance for twin pregnancies, contribute to improved antenatal care, and inform wider public health strategies.