But what if you had irregular menstrual cycles, and your LMP does not hold much relevance for you? Or what if you simply don't know when you had your last period? How will you know when your baby is due in those cases? Women who either had very irregular cycles before falling pregnant, or have no idea when they last menstruated, would normally face the suggestion of carrying out an early ultrasound to establish the gestational age of their fetus. This is done early on for several reasons. First, ultrasound is more effective as a means of determining the age of a fetus early on in pregnancy. The earlier an ultrasound is done the higher the chance that it will show gestational age correctly.
And the second reason? Doctors like knowing these things, and they can't stand being in the dark about your "due date", even early on in the game. Following your fundal height, which is the length of your abdomen, measured from the bottom of your pelvic bone to the top of your uterus (as soon as it gets big enough to be palpated) is another way of determining the estimated due date, and one that is favored by midwives. Of course, as with ultrasound, the only minor problem is that every baby develops differently, and every mother's uterus grows at different speeds. Both these methods, at the end of the day, should offer more of a guideline than anything else. Please think twice before allowing yourself to be induced because your healthcare provider told you that you were "overdue" after determining your due date in one of these ways. Babies tend to have a way of being born exactly when they are ready.