Your expected date of delivery or EDD is usually calculated from the first day of your last menstrual period (LMP). This is done by adding 7 to the day and adding 9 to the month (if LMP falls on January to March) or adding 7 to the day and subtracting 3 to the month (if LMP falls on April to December). For example, if your LMP is January 7, 2009, then your EDD is October 14, 2009. If your LMP is May 2, 2009, then the EDD is February 9, 2010. The EDD is approximately equivalent to 40 weeks age of gestation. However, according to the American College of Obstetricians and Gynecologists, only 5 % of babies are born on their exact EDD. But this is nothing to worry about, because your baby is still considered a term baby if born 3 weeks before or 2 weeks after your EDD (37-42 weeks).

Delivering your baby at less than 37 weeks entails a lot of complications because of the issue of fetal lung maturity. The baby’s lung may still be immature, resulting to acute respiratory distress syndrome and even death. However, prolonging the age of gestation is certainly not a good idea in order to address this fatal complication. Passing 42 weeks of gestation with the baby still undelivered, known as post-term pregnancy, is as risky as delivering the baby at less than 37 weeks.

Roughly 10% of babies are not delivered by 42 weeks and the most common cause is simply a miscalculation of due date. This is particularly common in women who have irregular cycles, have been on recent hormonal birth control, or who have first trimester bleeding. Hence, only 2% are really true post-term babies.

Although rare, post-term pregnancy is literally dangerous both to the mother and to the baby. First, as your pregnancy gets past its due date, the link between you and the baby which is the placenta, may stop functioning efficiently as it had before. This means that the nutrients and oxygen are not maximally delivered to the baby, leading to fetal distress and fetal death. Secondly, as pregnancy matures, the volume of amniotic fluid becomes less and less. When this occurs, there is an impending danger for the umbilical cord to get compressed, further compromising oxygen and nutrient supply to the baby. Some experts theorize that umbilical cord compression also triggers the baby to pass out meconium (the baby’ first bowel) into the amniotic fluid which he could aspirate into his lungs, and the baby could die in utero. Third, as time passes your baby has gained considerable weight and grows too big (called macrosomic babies) that it makes it harder to deliver vaginally. This may cause physical trauma to the baby such as clavicular fractures and nerve injuries, as well as perineal trauma to the mother. Lastly, post-term pregnancy also increases the risk of cesarean section due to fetal distress.

So, if you reach 41 or 42 weeks and you still have not delivered your baby, be wary. It is important for you to be in close contact with your health care provider at this time. Your health care provider will conduct some tests to check the well-being of your baby through ultrasound, non-stress test, or biophysical profile. If the tests show that the baby is active and the amniotic fluid is adequate, your obstetrician may decide to buy a little time until your labor starts naturally, but with close monitoring at scheduled intervals. But if the tests show that the baby is in danger should the pregnancy be further prolonged, your obstetrician will decide to terminate the pregnancy either by induced labor or c-section, whichever is deemed safe.

However, since no single test among the three mentioned above has been shown to be superior to any other, result of any of these tests is not taken lightly. For this reason, some health care providers recommend inducing labor at 41 weeks as long as the pregnancy is accurately dated and the baby can tolerate induced labor. If any problems occur during labor, a C-section delivery will be done immediately.

The bottom line is that no baby should die because of the complications brought about by post maturity. Post maturity can be prevented as long the mother is mindful of her due date and works closely with her health care provider through regular prenatal check-ups. The outmost care that you have devoted wholeheartedly to yourself and to your baby for the past 40 weeks, just to make sure your baby will be born healthy should not be put to waste just because you tend to be laidback when it comes to remembering dates. Remember, the life of your bundle of joy is at stake here.