In twin pregnancies, prematurity is one of the most frequent risks. If the chances of having a baby's delivery before term is almost six percent, in premature births the odds increase proportionally to the number of babies. With two babies, the risk rises to almost 50 percent.
In the case of two babies, the average duration of pregnancy is usually of 37 weeks, an ideal week to give birth, according to a study by a group of scientists from the Mary Queen University in London.
When twins do not share placenta, childbirth should occur at week 37; when they share it, in week 36.The research, published in the British Medical Journal, analyzed 32 studies published in the last 10 years, which included a total of more than 35,000 twin pregnancies: 29,685 bicorial (with independent placentas), and 5,486 monochorial pregnancies (with shared placenta). The objective was to determine the ideal period for childbirth, that is, the one that would help reduce the rate of fetal death.
A point that the authors of the study highlight is the distinction between the two types of twin pregnancies: dichorionic twin pregnancy, in which fetuses do not share placenta, and monochorionic twin pregnancy, in which they do share it.
In the first case, childbirth should occur at week 37, unlike a monochorionic pregnancy, which would have to do so. in week 36 of pregnancy. In the latter, according to the authors, there is no clear evidence to support the induction of labor before the 36th week of pregnancy.
Javier Zamora Romero, head of the Biostatistics Unit of the Ramón y Cajal University Hospital and co-author of the research, explains:
"The risk of fetal death is thirteen times higher in multiple monochorionic pregnancies and six times higher in dichorionic pregnancies, compared to common or simple pregnancies."
The researchers also refer to the neonatal mortality in babies born after 34 weeks of gestation. As of this stage, the risk of neonatal death is higher in pregnancies of monochorionic twins than fetal death.
After birth, these babies are more likely to need assisted ventilation, suffer respiratory difficulties, require admission to the Intensive Care Unit (ICU) or develop septicemia, a blood infection that, if not treated in time, can develop in sepsis causing an organic failure.
Not before week 36
For babies born between 26 and 33 + 6 weeks gestation, the risks increase. According to the study, bronchopulmonary dysplasia, necrotizing enterocolitis or abnormal results in cranial ultrasound examination and retinopathy can be added to the above complications.
The authors point out that the real risk of intrauterine fetal death at the end of pregnancy "could be higher than the estimates calculated at work due to the planning practices of the time of delivery applied to multiple pregnancies." In conclusion of the authors, " the study provides an exhaustive review of the estimates comparing the risk of fetal death and neonatal mortality at different gestational ages, information necessary for the planning of delivery of uncomplicated twin pregnancies. "
