Article type
Year
Abstract
Background: Uncontrolled studies suggest that in vitro fertilization (IVF) twins have increased rates of poor perinatal outcomes compared to spontaneously conceived twins such as preterm delivery and low birth weight, hence warranting increased antenatal monitoring Objective: To determine if there is a difference in the incidence of poor obstetric outcomes in IVF twins compared with spontaneously conceived twins matched for maternal age.
Methods: Search Strategy: Medline and EMBASE were searched using comprehensive search strategies.
Selection criteria: Controlled studies of twins conceived by IVF or IVF/ICSI (intracytoplasmic sperm injection), with transfer of fresh or cryopreserved (frozen) embryos in women with infertility, and/or whose partners are subfertile or infertile, compared with spontaneously conceived twins who are matched for maternal age.
Data collection and analysis: Two reviewers assessed titles and abstracts, and extracted data. Quality assessment was performed using the Cochrane Handbook s guidelines for observational studies based on four types of potential biases: selection, performance, attrition and detection bias. Each was rated as unbiased , biased and unknown because of no or unclear reporting . Meta-analysis was performed using a random effects model.
Results: Eleven case-control studies were included; a maximum of eight studies reported on any one outcome. By only including studies which matched for maternal age, (6) studies with the most significant selection bias were excluded. Many studies also matched for parity. Given the retrospective nature of the studies, attrition bias appeared negligible, however, performance and detection bias may have occurred. IVF twins have an increased risk of preterm delivery from 32-36 weeks gestational age (OR 1.48, 95% CI 1.05-2.1). Compared to spontaneously conceived twins matched not only for maternal age but also for parity, IVF twins had a trend towards preterm delivery before 37 weeks gestational age (OR 1.47, 95% CI 0.99-2.19). IVF twins were at an increased risk for admission to NICU (OR 2.23, 95% CI 1.64-3.02). There was an increased rate of caesarian section among IVF twins (OR of 1.39, 95% CI 1.21-1.59), which appeared to be mainly elective. There were no significant differences in the proportion of small for gestational age twins or the rate of congenital malformations.
Conclusions: Based on the results of this meta-analysis of case-control studies, IVF twins are at increased risk of preterm delivery, admission to NICU and birth by caesarian section compared to spontaneously conceived twins matched for maternal age.
Methods: Search Strategy: Medline and EMBASE were searched using comprehensive search strategies.
Selection criteria: Controlled studies of twins conceived by IVF or IVF/ICSI (intracytoplasmic sperm injection), with transfer of fresh or cryopreserved (frozen) embryos in women with infertility, and/or whose partners are subfertile or infertile, compared with spontaneously conceived twins who are matched for maternal age.
Data collection and analysis: Two reviewers assessed titles and abstracts, and extracted data. Quality assessment was performed using the Cochrane Handbook s guidelines for observational studies based on four types of potential biases: selection, performance, attrition and detection bias. Each was rated as unbiased , biased and unknown because of no or unclear reporting . Meta-analysis was performed using a random effects model.
Results: Eleven case-control studies were included; a maximum of eight studies reported on any one outcome. By only including studies which matched for maternal age, (6) studies with the most significant selection bias were excluded. Many studies also matched for parity. Given the retrospective nature of the studies, attrition bias appeared negligible, however, performance and detection bias may have occurred. IVF twins have an increased risk of preterm delivery from 32-36 weeks gestational age (OR 1.48, 95% CI 1.05-2.1). Compared to spontaneously conceived twins matched not only for maternal age but also for parity, IVF twins had a trend towards preterm delivery before 37 weeks gestational age (OR 1.47, 95% CI 0.99-2.19). IVF twins were at an increased risk for admission to NICU (OR 2.23, 95% CI 1.64-3.02). There was an increased rate of caesarian section among IVF twins (OR of 1.39, 95% CI 1.21-1.59), which appeared to be mainly elective. There were no significant differences in the proportion of small for gestational age twins or the rate of congenital malformations.
Conclusions: Based on the results of this meta-analysis of case-control studies, IVF twins are at increased risk of preterm delivery, admission to NICU and birth by caesarian section compared to spontaneously conceived twins matched for maternal age.