Ten things you should know about your uterus. (OK, some of them might not be essential knowledge, but they are very funny).
1. It looks like a shark’s brain
Weird, but true: the shape of a uterus (together with the vagina, ovaries and fallopian tubes) is really similar to that of a shark’s brain. Based on this striking similarity, shark week is one of the many synonyms for menstruation.
2. The ancient Greeks blamed the uterus for all ‘female illnesses’
Greek physician Hippocrates saw the womb as the place of origin of female diseases. He therefore considered menstruation to be the salvation of women. Young girls just before their menarche were most at risk: if the mouth of the womb wasn’t yet opened through sexual intercourse, the blood couldn’t flow out and would thus lead to ‘insanity and suicidal thoughts’. Hippocrates thought ‘wandering wombs’ (yes, back then it was believed a uterus could move freely through the female body) caused complaints, especially typical female problems such as mood swings and erratic or emotional behaviour. That’s also why the word ‘hysteria’ comes from ‘hystera’, the Greek word for uterus.
3. It prepares itself for pregnancy 500 times
A womb prepares itself for pregnancy about 500 times in a woman’s lifetime. This also means you get around 500 periods during your life. If you do get pregnant, the uterus creates an entire other organ to feed the baby: the placenta.
4. Human wombs look like upside-down pears
Human wombs look like upside-down pears. In other mammals, the uterus looks different. A lot of them, like cows, deer and pigs, have a bicornuate uterus, with two big compartments (horns) that both can carry multiple offspring. In humans, having a bicornuate or ‘heart-shaped’ uterus is considered a uterine malformation. Other types of uteruses that occur in the animal kingdom are the biparitite (which horses have) and the duplex (which can be found in rats, rabbits and guinea pigs).
5. It has four major regions
A uterus has four major regions. The upper end, the fundus, is connected to the fallopian tubes, while the lower end, the cervix opens into the vagina. Then there’s a body (corpus) which is the main part, located directly below the fallopian tubes, and the uterine isthmus, the lower region which connects to the cervix. Lining the inner cavity of the uterus is the endometrium, a moist mucous membrane which changes in thickness during the menstrual cycle. The endometrium consists of a basal layer (which is always there) and a functional layer (which is shed during menstruation).
6. It recedes when aroused
When you’re sexually aroused, the cervix recedes back closer to the uterus body. This causes the vagina to lengthen for easier intercourse.
7. It’s mega stretchy
A normal uterus measures about 7.5 cm (3 inches) long and 5 cm (2 inches) wide, almost the same size as a mandarin or a clenched fist. During pregnancy, however, it stretches and gets bigger. A lot bigger. It expands to the size of a grapefruit during the first trimester, gets as big as a papaya during the second, and finally in the third trimester it has reached the dimensions of a watermelon. Also its weight increases; before getting pregnant it’s around 60 grams (a bit over 2 ounces), and at the end of the pregnancy the uterus alone weighs about 1 kilo (2.2 pounds). After giving birth for the first time, the womb shrinks again which takes around six weeks, but will stay a bit larger than before getting pregnant. After the menopause, it reduces in size.
8. Not all women have one
Not all women have a uterus. Approximately 1 in every 4,500 to 5,000 female babies is born with the Mayer Rokitansky Küster Hauer Syndrome (MRKH), a congenital disorder that affects the female reproductive tract. These girls don’t have a uterus (or a vagina) and won’t get any periods. The condition is mostly only diagnosed when girls are between 15 and 18 years old and their menstruation still hasn’t started.
9. Some women have two
Uterus didelphys is a rare condition in which a woman is born with two uteruses. This happens when during the forming of the reproductive system in the fetus, the Müllerian ducts don’t join together as they’re supposed to do, but each turns into its own womb. In some cases, a double vagina is created as well. Uterus didelphys is thought to affect 1 in every 3,000 women; it may even go undetected as many of them don’t have any symptoms and only find out during a pelvic exam. These women often have difficulty conceiving, but this isn’t always the case.
10. It can be transplanted
In uterine transplantation, a healthy uterus is transplanted into a woman without uterus. This surgical procedure was first researched in 1918 and various attempts, with mixed results, followed in Germany (1931), Saudi Arabia (2000) and Turkey (2011). In September 2014, the first baby was born from a transplanted womb, in Sweden; his mother, who was born without a uterus, received one from a friend who had already gone through menopause. In the USA, the first successful birth after a uterine transplantation took place in 2017, and in the UK, doctors are currently preparing for the first uterus transplant to take place later this year.