Home monitors designed to measure the frequency of uterine contractions do not improve identification of women likely to give birth early. Alternative methods such as measuring the cervix or analysing foetal fibronectin were also found to have little bearing on premature birth, suggesting that it is almost impossible to predict when this is likely to occur.
Dr Jay Iams and colleagues from the US National Institute of Child Health and Human Development investigated whether the use of ambulatory monitors could accurately predict premature birth in 306 women who joined the study between 22 and 24 weeks of pregnancy. The monitors can be worn for up to 10 weeks, and transmit information to a central office where signs of unusual uterine activity are recorded and analysed, and can be passed on to healthcare professionals if required.
A slightly higher frequency of contractions was observed in women who went on to give birth prematurely, but no threshold frequency could be defined in order to allow effective prediction of premature labour.
Dr Nancy Green, acting director of the US-based March of Dimes Birth Defects Foundation, said, "Once again, we see that it's nearly impossible with the technology we have today to accurately predict who is going to give birth to a premature baby. If we truly want to help more babies be born healthy and lead healthy lives, we need more research aimed at preventing prematurity from occurring in the first place."