Older mothers do not confer greater perinatal risk to dichorionic diamniotic twins

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.

Women Aged over 40 with Twin Pregnancies Have a Higher Risk of Adverse Obstetrical Outcomes

Maternal age is related to a higher risk of adverse maternal, fetal, and neonatal outcomes in twin pregnancies. However, whether this increase in adverse outcomes is due solely to age or due to risk factors that are more common in women over 40 remains unknown. The aim of this study is to assess if maternal age over 40 years old is an independent risk factor for obstetric adverse outcomes in dichorionic diamniotic twin gestations. In this single-center retrospective cohort study, we compared the obstetric outcomes of women with dichorionic diamniotic twin pregnancies below and over 40 years of age. A twin pregnancy cohort enrolled between 2013 and 2019 was included in the study. Maternal, fetal, and labor complications were recorded. A total of 510 women were analyzed in two groups: 266 women below 40 years old and 244 women over 40 years old. Maternal age over 40 increased the odds of maternal (aOR = 1.9 (1.3; 2.9); p-value = 0.002), fetal (aOR = 1.8 (1.0; 3.0); p-value = 0.037), and labor complications (aOR = 2.5 (1.3; 4.6); p-value = 0.004). Maternal age over 40 years was the most important factor increasing the odds of having a caesarean section (C-section). Over 40 years old was an independent risk factor for complications in dichorionic diamniotic twin pregnancies.

Pregnancy and neonatal outcomes of twin pregnancies - the role of maternal age

OBJECTIVES

We aim to study the association of maternal age with maternal and neonatal complications in twin pregnancies.

METHODS

A retrospective cohort study of dichorionic-diamniotic twin pregnancies stratified into three groups according to maternal age ("A" <25, "B" 25-34 and "C" 35-44 years old). Outcome measures included pregnancy, delivery and neonatal complications. A sub-analysis of in vitro fertilization pregnancies only was conducted.

RESULTS

Compared with younger women (groups A [n=65] and B [n=783]), older women [group C (n=392)] demonstrated significantly higher rates of gestational diabetes mellitus (B 6.6% vs. A 0%, p =0.027, C 10.2% vs. B 6.6%, p =0.032), were more likely to undergo cesarean deliveries (C 66.6%, B 57.6%, A 52.3%, p =0.007), and were at increased risk of having more than 20% difference in weight between the twins (C 24.5%, B 17.4%, A 16.9%, p =0.013). Other outcomes, including preeclampsia, did not differ between the groups. A sub-analysis of the in vitro fertilization only pregnancies was performed. Compared with younger women (groups A [n=18] and B [n=388]), older women (group C [n=230]) underwent more cesarean deliveries (p=0.004), and had more than 20% difference in weight between the twins (p<0.004). Other outcomes, including gestational diabetes mellitus rates and preeclampsia, did not differ between the groups.

CONCLUSIONS

Women at advanced maternal age with dichorionic twin pregnancies had significantly higher rates of gestational diabetes mellitus, cesarean deliveries and fetal weight discordancy as compared with younger women. In contrast, the incidence of preeclampsia was not affected by maternal age.

Twin versus singleton pregnancy in women ≥ 45 years of age: comparison of maternal and neonatal outcomes

Objectives: The aim of the study is to compare the effect of very advanced maternal age (≥45 years) on maternal and neonatal outcomes of twin and singleton pregnancies.Materials and methods: This retrospective cohort study included women ≥ 45 years of age who gave birth to twins. Each was randomly matched to two women ≥ 45 years of age who gave birth to singletons within 7 days of the study subject. Data on maternal age, gravidity, parity, background medical information, body mass index at conception, number of fetuses, mode of conception (either spontaneous or assisted reproductive technology [ART]), mode of delivery, and gestational age at delivery were extracted from a real-time computerized database.Results: The data of 75 twin pregnancies of women aged ≥ 45 years were compared with those of 150 singleton pregnancies matched for maternal age. There were significantly more cases of hypertensive complications among the twin pregnancies compared to the singleton pregnancies (41.33 versus 14.00%, respectively, OR = 3.33, 95% CI = 2.26-8.30, p = .000) and more cases of preeclamptic toxemia (29.33 versus 12.00%, respectively, OR = 3.04, 95% CI = 1.51-6.13, p = .001). The duration of twin pregnancies was much shorter compared to singleton pregnancies, with a higher incidence of deliveries prior to 37 weeks' gestation (56.00 versus 8.00%, respectively, OR = 14.64, 95% CI = 6.94-30.85, p = .000), and deliveries prior to 34 weeks' gestation (22.67 versus 2.00%, respectively, OR = 14.36, 95% CI = 4.06-50.86, p = .000). More infants of twin pregnancies had a low birth weight (68.00 versus 10.00%, respectively, OR = 19.13, 95% CI = 10.14-36.06, p = .000), and many had a very low birth weight (10.67 versus 0.67%, respectively, OR = 17.79, 95% CI = 2.33-135.97, p = .000). The infants of twin pregnancies also included more cases of intubation (10.00 versus 0.00%, respectively, p = .000), more cases of hypoglycemia (12.67 versus 5.33%, respectively, OR = 2.57, 95% CI = 1.09-6.08, p = .026), and were admitted much more often to the neonatal intensive care unit (36.00 versus 8.00%, respectively, OR = 6.47, p = .00, CI = 3.29-12.74).Conclusions: Women ≥ 45 years of age with twin pregnancies and their neonates sustain more severe adverse outcome compared to matched pairs of singleton pregnancies. It is recommended that a single embryo transfer should be offered in preference to multiple embryos when those women are undergoing ART.

Advanced maternal age and perinatal outcome in twin pregnancies: a meta-analysis

Objective: The current meta-analysis evaluates the perinatal outcomes of twin pregnancies in pregnant women 35 years or older (advanced maternal age) compared with less than 35 years at the time of delivery.Study design: A search was conducted up to March 2018. Electronic databases that were used in our research included; Embase (NO Medline), Ovid Medline, Cochrane Central Register of Controlled Trials, and Web of Science. Inclusion criteria were twin pregnancies; a comparison between pregnant women aged ≥35 years versus <35 years at the time of delivery and reported perinatal outcomes. Review articles, case reports, and case series were excluded. Data analysis was performed using the Cochrane's Review Manager 5.3 software. Pooled odds ratio for dichotomous outcomes or mean difference for continuous outcomes were calculated using a random effects model. I² test was performed to assess heterogeneity. The quality of each accepted article was assessed using the Newcastle-Ottawa Scale.Results: Our search yielded 1622 publications, of which 25 were assessed for eligibility. A total of 13 studies met our final inclusion criteria. In twin pregnancies, advanced maternal age was associated with a lower incidence of preterm birth prior to 37 weeks' gestation (OR 0.89 [95% CI 0.83-0.95]) compared with women under 35 years at the time of delivery. Gestational diabetes (OR 1.57 [95% CI 1.24-1.98]) and cesarean deliveries (OR 1.69 [95% CI 1.52-1.87]) were significantly higher among women in the advanced maternal age group. All other measured outcomes, such as preterm delivery before 32 weeks' gestation, hypertension disorders, small for gestational age, birth weight under 2500 or 1500 g, need for neonatal intensive care admission and perinatal death were comparable between the groups.Conclusions: This meta-analysis implies that advanced maternal age mothers in the setting of twin pregnancy is associated with comparable outcomes to nonadvanced maternal age mothers. The only outstanding differences were higher rates of GDM and cesarean deliveries in the advanced maternal age (AMA) group.

Twin pregnancy in women above the age of 45 years: maternal and neonatal outcomes

Childbearing age continues to rise and, with the increasing implementation of assisted reproductive technology (ART), the number of multiple pregnancies has also risen. This is a retrospective cohort study on maternal and neonatal outcomes of the twin pregnancies of 57 women aged ≥45 years compared to 114 younger women who gave birth in our institution between January 2011 and August 2015. Data were extracted from the real-time computerized database. The rates of hypertensive complications and pre-eclampsia (PE) were much higher in the study group compared to the controls (24/57 vs. 19/114, P=0.000 and 15/57 vs. 13/114, P=0.013, respectively). The respective incidence of very low birth weight (VLBW) was also significantly higher (14/114 vs. 12/228, P=0.021). Infants in the study group required four times more intubation and had a higher admission rate to the neonatal intensive care unit (NICU) compared to control infants (14/114 vs. 6/228 P=0.000 and 42/114 vs. 57/228, P=0.023, respectively). We conclude that women older than 45 years with twin pregnancies have higher maternal and perinatal complications with worse outcomes in comparison with younger women. When pregnancy is attempted via ART, embryo transfer of only one embryo should be considered in this age group.

Effect of advanced maternal age on perinatal outcomes in twins: the impact of chorionicity

PURPOSE

In contrast to singletons, twins born to older mothers have lower rates of perinatal mortality than twins born to younger mothers. We examined whether differences in chorionicity could explain this unexpected maternal age effect.

METHODS

We used population-based data on twins born to mothers aged 20-29 (n = 3702) and ≥35 years (n = 1880) in the North of England, UK, 1998-2007. We calculated rate ratios (RR) and 95% confidence intervals (CIs) to estimate the effect of maternal age; adjusted RRs (ARRs) were estimated by the use of generalized estimating equations for Poisson regression controlling for chorionicity and other confounders.

RESULTS

Older mothers had a lower proportion of monochorionic twins (17.6% vs. 24.3%, P < .01); lower neonatal (RR, 0.57; 95% CI, 0.34-0.95) and perinatal mortality (RR, 0.74; 95% CI, 0.53-1.04). Adjustment for chorionicity attenuated these associations (ARR, 0.59; 95% CI, 0.35-0.98 and ARR, 0.80; 95% CI, 0.57-1.12, respectively) and after further adjustment for additional factors, both associations became nonsignificant. Older mothers had greater rates of small-for-gestational-age infants (ARR, 1.59; 95% CI, 1.24-2.05), and cesarean delivery (ARR, 1.31; 95% CI, 1.16-1.48).

CONCLUSIONS

Perinatal death rates were lower but not statistically different for twins born to older versus younger mothers. This association was attenuated by adjustment for chorionicity.