Baby dating scan be wrong our life dating
When an ultrasound is performed, measurements of the head, abdomen, thigh, and amount of amniotic fluid are done.These measurements are computed automatically in the ultrasound machine’s software.If the blood test is taken too early because your dates are wrong, this might lead to you being given a high risk factor when, in fact, your baby is developing normally. The length of your pregnancy is calculated from the first day of your last menstrual period (LMP), even though you don't actually conceive until 14 days after your LMP, and later than this if your cycle is longer than 28 days.The LMP is used because most women know when their last period was, but may not know when they actually conceived.The simple rule in ultrasound is that when the due date based on ultrasound doesn’t vary from the mother’s dates by more than a week, stick with the mother’s dates; if the ultrasound disagrees by more than a week to ten days, it becomes wiser to rely on the ultrasound.This doesn’t apply later on in pregnancy for the reasons above. If two ultrasounds one month apart determine coinciding due dates, especially if they agree with the mother’s date based on a last period, the accuracy can be within a couple of days. Babies have their own clock and can come anywhere from three weeks before this exquisitely determined due date till two weeks after.
Before twelve weeks, it’s difficult to measure much more. In the second trimester, (past the first 12 weeks), the other measurements can be added.Your Facebook name, profile photo and other personal information you make public on Facebook (e.g., school, work, current city, age) will appear with your comment.Having a scan in the first few weeks of pregnancy can be a thrilling experience. Bear in mind that you may need a second scan before you know for certain if all is well.This is because hormones measured in the blood test vary at stages of the pregnancy.So if you have a blood test at 14 weeks, the results would be of no help if a scan later revealed you were actually 16 weeks pregnant when the blood was taken. The main reason for the scan is to work out how many weeks pregnant you are, and to estimate your due date.
Therefore, measurements taken later on, when babies begin to grow at different rates among pregnancies, yield increasingly inaccurate dating of pregnancy.