More than 1,700 pregnant women in South Australia have reportedly been given the wrong “due date” due to a technical error in their computerised medical records. This has prompted concerns some women may have had an early induction of labour as a result. According to today’s ABC report , most of the women whose records are affected have since given birth, while about 100 are still pregnant.
Not all women have yet been notified of the error. An investigation is now under way to find out how the error happened and if the incorrect due dates have impacted care. But how accurate are due dates anyway? And what happens when we get them wrong? What people normally call their “due date” is actually the estimated day your baby will be born.
There are a variety of online tools to work out this date, based on something called Naegele’s rule , named after the German obstetrician Franz Naegele (1778-1851) . Naegele’s rule works out your estimated due date by taking the first day of your last menstrual period, adding seven days, then adding 40 weeks (nine months). Naegele’s rule has limitations.
First, it assumes all menstrual cycles are 28 days long and ovulation occurs on day 14. It also relies on the woman knowing the date of her last menstrual period. This method is still used by doctors and midwives to work out the expected date of birth.
However, there is an increased reliance on using an ultrasound between eight and 16 weeks to predict the due date. This measures the.