Tocolytic drugs ineffective for premature birth after 30 weeks

The use of tocolytic drugs in cases of threatened premature birth after 30 weeks of pregnancy does not improve the baby's health. This is shown by the largest study concerning the effectiveness of tocolytic drugs on the health of babies, led by Amsterdam UMC, the results of which were published today in The Lancet. 

Worldwide, 1 in 10 pregnancies result in premature birth. Children born prematurely face a higher risk of mortality and serious health problems, both in the short and long term. As a results, tocolytic drugs have been used a standard treatment for many years in women who threaten to given birth prematurely, after 24 weeks and before 34 weeks of gestation. The rationale behind their use is that prolonging pregnancy grants the baby with extra time to develop, thereby reducing the risk of health problems. 

Whether prolongation of pregnancy by using tocolytic drugs actually benefits the health of the baby has not been substantiated by research until now."

Martijn Oudijk, professor of prevention and treatment of premature birth, Amsterdam UMC

The study, funded by the ZonMw programme Good Use of Medicines, was conducted in twenty-four Dutch hospitals that are part of the Dutch Consortium for Healthcare Evaluation and Research in Obstetrics and Gynaecology, as well as two hospitals in England and Ireland. The study involved 755 women with threatened premature labour (TPL) between 30 and 34 weeks of pregnancy, half of whom received a tocolytic drug, while the other half received a placebo.

"This is the largest placebo-controlled study ever performed investigating the effects of tocolytic drugs on the baby's health. Our results showed no difference whatsoever. There was no benefit but also no harm done," says Amsterdam UMC PhD-student Larissa van der Windt. 

According to Oudijk, it is time to reconsider current medical practice: "We have to ask ourselves whether tocolytic drugs should continue to be a standard treatment for TPL after 30 weeks of pregnancy. The purpose of delaying childbirth is to give newborns a better start and improve their health. Premature birth often has a medical cause, such as an infection or problems with the placenta. A prolonged stay in the uterus longer might actually be harmful."

In large hospitals in Canada and Ireland, the use of tocolytic drugs after 30 weeks of pregnancy has already been discontinued. "It is high time that we start working on adjusting guidelines, both in the Netherlands and abroad," says Oudijk.