From time to time a woman goes in for her early pregnancy scan and they’re telling her that she is ten weeks pregnant and she is thinking well how can that be I only met him eight weeks ago how can I be 10 weeks pregnant well health care providers all use the first day of the last menstrual period as the first week of pregnancy even though you are not really pregnant for at least two more weeks, the gestational age is really only eight weeks but by menstrual age baby is 10 weeks and most clinics and hospitals use menstrual dates now how do you accurately estimate your due date it’s very easy really.
This is going to be based on the woman’s last menstrual period and an important note for this it’s going to be based on the first date of her last menstrual period, if she started menstruating on Monday we would come from that Monday so it’s going to be the very first day of the last period. Now it is kind of got a formula into it really you just add a year subtract three months and then add seven days. This takes into account a 28 week cycle, you know not all women have a 28 week cycle then it also is going to account for the fact that a typical pregnancy is going to be 280 days that equates to 40 weeks so those are assumptions. Our assumptions are the women has a typical 28 week cycle meaning on day 14 she’s going to have the LH surge or releasing the egg and then also taking into the effect for our estimated date of delivery that the deliver the pregnancy will last 280 days or 40 weeks so we use this formula. Remember the date of conception is that 14 days in the woman’s cycle day 14 when the LH surge happens that’s when the egg is released egg and the sperm meeting that is going to be your date of conception that’s not going to be the date that we’re basing it off. We are basing it off the first day of her last menstrual period. More explained here: http://www.dodgecentralcu.com/how-to-figure-out-your-due-date-due-date-calculator/
There are two ways to figure out how far along a woman is; one is going off her previous cycle history if a woman has had a history of regular periods then they’ll ask you what your last period date was and if you are sure about it then it is pretty easy to figure out how far along you are but if a woman has irregular periods or you don’t know when your period was that an ultrasound is the best way to date your pregnancy. A fetus will grow at a pretty consistent rate during the first trimester and so when they did the ultrasound at six weeks and figured that your baby was six weeks along that is the best and most accurate thing that we can go by in fact if a baby starts to be either larger or smaller than they should be in the second or third trimester a lot of times your gynecologist would want to know if you had an early ultrasound because that’s the best way to figure out if your due dates are accurate so because your due date was based on an early ultrasound you can say that it is really accurate.
I hope this points helps you in your quest to find out your pregnancy due date.