Pregnancy outcomes of twins after in vitro and spontaneous fertilization

Assisted reproductive technology and hypertensive disorders of pregnancy: systematic review and meta-analyses

Background

Hypertensive disorders of pregnancy (HDP) is one of the most common pregnancy complications and causes of maternal morbidity and mortality. Assisted reproductive technology (ART) has been associated with adverse pregnancy outcomes, including HDP. However, the impact of multiple pregnancies, oocyte donation, as well as fresh and frozen embryo transfer needs to be further studied. We conducted a systematic review and meta-analyses to evaluate the association between ART and HDP or preeclampsia relative to spontaneous conception (SC).

Methods

We identified studies from EMBASE, MEDLINE, and Cochrane Library (up to April 8, 2020) and manually using structured search strategies. Cohort studies that included pregnancies after in vitro fertilization (IVF) with or without intracytoplasmic sperm fertilization (ICSI) relative to SC with HDP or preeclampsia as the outcome of interest were included. The control group was women who conceived spontaneously without ART or fertility medications. The pooled results were reported in odds ratios (OR) with 95% confidence intervals based on random effects models. Numbers needed to harm (NNH) were calculated based on absolute risk differences between exposure and control groups.

Results

Eighty-five studies were included after a screening of 1879 abstracts and 283 full text articles. Compared to SC, IVF/ICSI singleton pregnancies (OR 1.70; 95% CI 1.60–1.80; I² = 80%) and multiple pregnancies (OR 1.34; 95% CI 1.20–1.50; I² = 76%) were both associated with higher odds of HDP. Singleton pregnancies with oocyte donation had the highest odds of HDP out of all groups analyzed (OR 4.42; 95% CI 3.00–6.51; I² = 83%). Frozen embryo transfer resulted in higher odds of HDP (OR 1.74; 95% CI 1.58–1.92; I² = 55%) than fresh embryo transfer (OR 1.43; 95% CI 1.33–1.53; I² = 72%). The associations between IVF/ICSI pregnancies and SC were similar for preeclampsia. Most interventions had an NNH of 40 to 100, while singleton and multiple oocyte donation pregnancies had particularly low NNH for HDP (16 and 10, respectively).

Conclusions

Our meta-analysis confirmed that IVF/ICSI pregnancies are at higher odds of HDP and preeclampsia than SC, irrespective of the plurality. The odds were especially high in frozen embryo transfer and oocyte donation pregnancies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03938-8.

Association between chorionicity and preterm birth in twin pregnancies: a systematic review involving 29 864 twin pregnancies

BACKGROUND

The perinatal mortality and morbidity among twins vary by chorionicity. Although it is considered that monochorionicity is associated with an increased risk of preterm birth in twin pregnancies, no systematic review exists evaluating this association.

OBJECTIVES

This systematic review was undertaken to assess the association between preterm birth and chorionicity in twin pregnancies.

SEARCH STRATEGY

We searched the electronic databases from January 1990 to July 2019 without language restrictions.

SELECTION CRITERIA

All studies on twin pregnancies where chorionicity and preterm birth were evaluated were included.

DATA COLLECTION AND ANALYSIS

Findings are reported as odds ratios with 95% confidence intervals. The estimates are pooled using random-effects meta-analysis.

MAIN RESULTS

From 13 156 citations, we included 39 studies (29 864 pregnancies). Monochorionicity was significantly associated with increased risk of preterm birth at ≤28, ≤32, ≤34 and <37 weeks in women asymptomatic and symptomatic for preterm labour (odds ratio [OR] 2.14, 95% CI 1.52-3.02, I²  = 46%, OR 1.55, 95% CI 1.27-1.89 I²  = 68%, OR 1.47, 95% CI 1.27-1.69, I²  = 60%, OR 1.66, 95% CI 1.43-1.93, I²  = 65%, respectively). Among those asymptomatic for preterm labour, significantly increased odds of preterm birth were seen for monochorionicity at gestations ≤34 weeks (OR 1.85, 95% CI 1.42-2.40, I²  = 25%) and <37 weeks (OR 1.75, 95% CI 1.22-2.53, I²  = 61%). Sensitivity analysis showed significantly increased odds of spontaneous preterm birth at ≤34 and <37 weeks for monochorionicity (OR 1.25, 95% CI 1.01-1.55, I²  = 0% and OR 1.41, 95% CI 1.13-1.78, I²  = 0%).

CONCLUSIONS

Monochorionicity is significantly associated with preterm birth at all gestations.

TWEETABLE ABSTRACT

In twin pregnancies, monochorionicity is associated with an increased risk of preterm birth at all gestations.

Perinatal outcome of monochorionic and dichorionic twins after spontaneous and assisted conception: a retrospective cohort study

Introduction

The aim of this study was to compare pregnancy outcomes in twin pregnancies after assisted conception and spontaneous conception, according to chorionicity.

Material and methods

Retrospective cohort study of 1305 twin pregnancies between 1995 and 2015. All spontaneous (n = 731) and assisted conception conceived (n = 574) twin pregnancies with antenatal care and delivery in University Medical Center Utrecht, the Netherlands, a tertiary obstetric care center were studied according to chorionicity.

Results

Maternal age and incidence of nulliparity were higher among the assisted conception twins. Hypertensive disorders also appeared to be more frequent in assisted conception pregnancies, which could largely be explained by the higher proportion of elderly nulliparous women in this group. Spontaneously conceived twins were born earlier than twins after assisted conception, with subsequent lower birthweights and more admissions to a neonatal intensive care unit with increased neonatal morbidity. Monochorionic twins had worse pregnancy outcomes compared with dichorionic twins, irrespective of mode of conception; monochorionic twins conceived by assisted reproduction had more neonatal morbidity (mainly respiratory distress syndrome and necrotizing enterocolitis) and late neonatal deaths compared with spontaneously conceived monochorionic twins.

Conclusions

Spontaneously conceived twins have worse pregnancy outcome compared with twins after assisted conception, probably due to a lower incidence of monochorionicity in the assisted conception group. The already increased perinatal risks in monochorionic twins are even higher in monochorionic twins conceived after infertility treatments compared with spontaneously conceived monochorionic twins, which warrants extra attention to these high‐risk pregnancies.