What the Phrase “Six Weeks of Pregnancy” Really Means
After the Supreme Court ruling to allow Texas to ban abortion after about six weeks of pregnancy , several people – I will not name them – showed that they had no idea how a week of pregnancy was counted. Guys, on the day you have sex to conceive , you’re already two weeks pregnant. And you may not even know you are pregnant until four or five weeks.
This is because gestational age (weeks of pregnancy) is not how much embryo or fetus you have in your body, but how long it has been since the first day of your last period . Let’s use the example of a woman (let’s call her Jane) with a perfect textbook cycle. She starts her period on January 1 and has sex only once in her life, resulting in a pregnancy. These dates can vary from person to person, so this is just an example:
- January 1: Jane starts her period. She loses the lining of the uterus. She’s definitely not pregnant.
- January 12 or so: She has sex.
- January 14: Ovulation (release of an egg from the ovary). Shortly thereafter, the egg meets one of the sperm obtained a few days ago.
- January 21: A developing embryo is implanted into her uterus. She is now pregnant, more precisely, in the third week of pregnancy .
- January 28: Pregnancy hormone levels are high enough for a very sensitive pregnancy test to detect.
- January 30: Jane, who follows the calendar like a hawk, notices that her period is delayed. She is over four weeks pregnant.
Thus, the earliest thing you can know about your pregnancy is “four weeks” gestation, which means that the embryo was implanted into your uterus for only one valid week and only existed for two weeks. But the dates are counted as if the pregnancy occurred on January 1st.
This is an optimistic example for many reasons. For example, most people don’t have their periods in their 28-day training cycle. If your period is, say, between 29 and 34 days, you won’t start thinking about them a little later. And that assumes that you are looking at the calendar; if you are not going to get pregnant, you may not realize that you are late until one or two weeks have passed. The American Prenatal Association notes that most women are aware of their pregnancy between four and seven weeks (that is, two to five weeks after intercourse that led to conception).
A missed period is not the best pregnancy signal for everyone. Some people have irregular periods, especially if they use contraception to skip or shorten their periods. In the meantime, there may be bleeding around that three-week mark when the embryo is implanted, and you might be thinking, “Hmm, my periods got a little easier and earlier than usual,” but not really worry about it. There are also medical reasons why a person may miss their periods for reasons other than pregnancy.
So what about pregnancy symptoms? For example, morning sickness usually does not appear until the fifth or seventh week, and some people do not have morning sickness at all.
If you go to the doctor or clinic for a pregnancy test, we add more time. Let’s say you think you might have a week’s delay and go to the clinic in a few days. You could easily go up to six weeks before taking the test at all.
This post was originally published in May 2019 in response to a similar law in Georgia . It was updated on September 3, 2021 in the context of the Supreme Court’s decision to maintain the Texas abortion ban.