Common sense often leads us to count pregnancy by months, but when a woman becomes pregnant and starts talking to her doctor, she learns that tracking by weeks is much more accurate. This is because changes happen very quickly in a developing baby, and counting in weeks allows these changes to be monitored, which wouldn’t make as much sense with months. But how can I know how many weeks pregnant I am? There is a simple and very effective method. Today we will talk about how to calculate pregnancy based on LMP. But first, do you know what this acronym means?
What is LMP?
It stands for “Last Menstrual Period.” It is simply the date of the first day of a woman’s last menstrual period, just as the term implies. Knowing the exact first day is important for calculating pregnancy by LMP, since the gestational calculation starts from there. If a woman is trying to get pregnant, it’s recommended that she write down the dates of her periods somewhere, since she will always be asked about it during exams, especially ultrasound scans. If a woman becomes pregnant unexpectedly, it’s a little harder to know the exact date, so it’s best to always keep a record of period dates, even to check if there’s been any birth control pill contraceptive error or another method failure.
Gestational Age Calculation
First, it’s important to know that pregnancy usually lasts between 37 and 42 weeks. The average is 268 days, which is 38 weeks, but it’s common for some pregnancies to end a bit earlier or later. To know how to count pregnancy by LMP, a woman needs to know the date of her last menstrual period and, from there, count the weeks. This is because it’s very difficult to know exactly on which day the egg was fertilized, so it became standard to count from the LMP. The definitive gestational age is adjusted at the first pregnancy ultrasound, which usually happens between 11 and 13 weeks of pregnancy. After this point, the woman can know exactly which stage of pregnancy she’s in, but this doesn’t mean she couldn’t already have a good idea before.
How to Calculate the Estimated Due Date?
It’s very difficult to calculate the exact day of delivery, but it’s possible to make an accurate estimate so the woman can prepare. This is also commonly called the probable due date. A doctor isn’t needed to work out this date once a woman has learned how to count pregnancy by LMP. What you need to do is basically calculate from the date of the first day of the last period and add 7 days and 9 months. If the last period started on February 1st, for example, the estimated date would be October 7th. But of course there’s a margin of error, as it’s normal for babies to be born a little before or after this date. Usually, a doctor will schedule weekly appointments starting from the 36th week of pregnancy, as a precaution, since from then on there is already a chance for labor to start at any moment.
How to Know the Gestational Age in Months?
As we’ve mentioned before, it’s very common for people to ask how many months pregnant you are, since the count in weeks is mostly used by doctors to track the baby’s development more precisely. But how do you convert the weeks into months? Actually, this is quite easy; just consider that every 4 and a half weeks equals one month. So, at 9 weeks you’d be 2 months pregnant, at 13 weeks, 3 months, and so on. This method is more for guiding people who aren’t familiar with the count in weeks, which is the most precise and important for you to know.
What if I Don’t Know the Date of My Last Period?
In this case, as we’ve already mentioned, you’ll need to wait for exams to know your gestational age for sure. However, from the first exams and professional assessment, it’s already possible to have a good estimate, and a woman will rarely be left not knowing how many weeks pregnant she is. Even if she can’t remember the exact date, she’ll probably have some idea of how long she’s been pregnant. Despite this convenience, it’s still recommended that women always write down their period dates, as there’s nothing better than tracking it yourself. Knowing how to calculate pregnancy isn’t just about knowing your baby’s growth stage, but also understanding the symptoms your body may present during each period, what is normal or not, and when you need to seek medical help. This is one of the most special moments in a woman’s life, and knowing how life is forming inside you brings immense joy. A unique feeling. So don’t depend only on exams to estimate your gestational age; learn how to count pregnancy based on the LMP and notice every change week by week. See also: How to Count Pregnancy Weeks Photo: pxhere