When a woman is trying to get pregnant and has a transvaginal ultrasound, the size of her uterus can spark some hope. Does a large uterus mean a baby is on the way? Unfortunately, that’s not exactly how it works…
The uterus of a woman who has never had children can be much smaller than that of a woman who has already given birth. As we know, the uterus is one of the most elastic organs in the human body1. It is capable of growing up to 100 times its size during pregnancy. Imagine that such a small organ, about the size of a closed fist, can eventually house up to 6 or 7 babies at the same time. Of course, nature did not design the uterus for so many babies at once, but it is strong enough to handle this feat until the sixth or seventh month of pregnancy.
The parameter assessed in ultrasound exams is the circumference, measured in terms of volume. For a “normal” uterus in women without children, the standard is 50cm³ to 90cm³. However, values around 30cm³ and even up to 160cm³ are also possible for women who have had one or more pregnancies. All of this depends on several factors that affect uterine size throughout life. And, of course, whether or not there is a pregnancy in progress. When the uterus is very large and the woman has never had children, it’s important to have some tests to check if everything is okay. It’s essential to make sure there isn’t a fibroid, a hormonal alteration, adenomyosis, or even a pregnancy.
Is It Possible to Diagnose Pregnancy by Uterine Size?
No, because there is no set standard for uterine sizes in pregnancy. As mentioned, this can vary greatly depending on a woman’s age, whether or not she has had children, whether she has had miscarriages and when her last pregnancy was, for example. For women who have already had children, a normal size is at most 160cm³. However, an even higher measurement can also be healthy depending on a range of variables. For instance, a twin pregnancy that has gone up to the 9th month of pregnancy leaving the uterus at 200cm³. Now, diagnosing pregnancy by uterine size is complicated. You can get an idea of what is happening, but confirmation only comes after 7 weeks of pregnancy, when it’s already possible to see the gestational sac, the baby, and the heartbeat on ultrasound.
But yes, women with an enlarged uterus are great candidates to be pregnant if they have missed their period. That’s because the uterus grows along with the endometrium after implantation. And this growth can be seen on an ultrasound. By the way, the endometrium can also be a hopeful sign for those trying to conceive if it has a trilaminar appearance and measures more than 12mm in thickness.
Women who have never had children and have a uterus above 100cm³ have a good chance of being surprised by a pregnancy. However, before getting your hopes up, you should investigate whether there are other factors causing this uterine enlargement.
A good example of uterine size in pregnancy is my own. Before I got pregnant, an ultrasound showed my uterus was about 87cm³. Right after ovulation, this number jumped from 87 to 103cm³. That gave me some hope. A few weeks later, already with a positive pregnancy test, my uterus appeared much larger, with clear signs of pregnancy (bigger, rounder, more voluminous) and measured about 150cm³. Remember, uterine measurements vary depending on factors such as:
- Woman’s height
- Age
- Weight
- History of infections or diseases
- Previous pregnancies
That’s why it is difficult to determine standard measurements for the size of a potential mom’s uterus. Every body is unique, and depending on the menstrual cycle, it can still change. The same woman may have a larger uterus than the previous month due to the intensity of the cycle2, for example.
Before you start celebrating because of uterine size, it’s worth checking your luteal phase. If your uterus is enlarged and your period is already late, there’s a chance you may be pregnant. If not, then wait for your period to be late and take an HCG test to clear up any doubts. Just to stress, in order to check the uterine measurements, you need to have a pelvic or transvaginal ultrasound. Talk to your gynecologist.
See also: Am I Pregnant Even If I’m Menstruating?
