Ivf pregnancy dating
After 18 weeks, the distance (in cm) between the fundus and pubic bone will be the same as the number of weeks from the last menstrual period. It is based on a series of measurements of the gestational sac and the fetus.The sonographer measures the baby from head to toe. It helps the doctor estimate the pregnancy week based on the growth of your baby (6).It gives you the estimated conception date and estimated due date along with the weeks of each trimester.It will also show your current pregnancy week, and many more weeks you have to reach a full-term pregnancy.[ Read: Growth Scan During Pregnancy ] You can start counting pregnancy weeks as soon as you calculate your due date based on your LMP.If there is not much difference between ultrasound measurements and LMP, the doctors may use the LMP to establish the due date.For instance, if your first-trimester ultrasound and LMP estimates fall within the same week, LMP is considered final.Unless you had an assisted conception and knew when the fertilization took place, LMP method is the only way to know the closest ovulation and conception dates (3).The doctors can help you with the exact calculation of weeks and months of pregnancy through other ways.
As you near the due date, you may have to start counting your pregnancy by days as – 39 weeks one day, 39 weeks two days, and so on (6).If there is a difference of one week or more, the ultrasound estimate is considered (4).Try our pregnancy due date calculator to know your due date.Menstrual period and ovulation period are calculated as the first two weeks of pregnancy as ovulation takes place two weeks after the first day of LMP.If you deliver the baby on the estimated due date, she is 38 weeks old, and not 40 (1).