“How can I be so far along when I only had sex a few weeks ago?”
This is a question our staff nurses get all the time at The Pregnancy Network. The simple answer? There are two ways of dating a pregnancy. Keep reading to learn about each one.
The First Day of Your Last Menstrual Period (LMP)
Dating your pregnancy from the first day of your last menstrual period is the method that will be used by your OBGYN. This is the only method that is reliably trackable. The first day of a woman’s LMP is used as the “starting point” for dating a pregnancy, even though it is understood that a woman cannot get pregnant on the first day of her period.
Conception
Conception refers to the moment an egg is fertilized after having sex. This is the true start of your pregnancy. However, the exact moment or day of conception is difficult to pinpoint. It is possible for conception to take place as many as 5 days after having sex. This is because sperm can remain viable up to 5 days after ejaculation. If a woman ovulates (a mature egg is released from her ovary) during this 5 day period, conception may occur during this window. A woman’s egg can only be fertilized 12 to 24 hours after being released from the ovary.
All of these factors make it complicated to determine the exact moment of conception. That is why a woman’s LMP is used instead.
How Far Along Am I?
“Assuming you have a typical 28 day cycle, if you take a positive pregnancy test on the first day of your missed period, then you would be considered 4 weeks pregnant by your LMP,” says Registered Nurse Lauren McClure. “If we were to date by conception, you would only be about two weeks pregnant.”
Click here to watch a short video of our staff nurse explaining these two ways of dating a pregnancy.
What To Do Next?
If you think you may be pregnant, we’re here to help. At The Pregnancy Network, we can offer a free pregnancy test to confirm your pregnancy as well as a free limited ultrasound. An ultrasound will allow you to get a more accurate gestational age. You will also be able to verify that the pregnancy is developing inside the uterus. This is important information for you to have as you make a decision about your pregnancy.
You are not alone; we are here to walk alongside you during and after your pregnancy. At your appointment, a staff nurse will talk with you about all your questions and concerns. You deserve to be fully-informed about all your options before making a decision. Click here to make a free appointment today.
Mary Holloman
Mary is the Communications Coordinator at The Pregnancy Network.