A lot happens during the roughly 40 weeks of pregnancy. You may expect some of the changes that occur during this time, but others may seem fascinating or even surprising.

Below are 30 facts and 5 myths about fertility, pregnancy, delivery, and more.

30 facts about pregnancy

1. The longest recorded pregnancy was 375 days. According to a 1945 entry in Time Magazine, a woman named Beulah Hunter gave birth in Los Angeles nearly 100 days after the average 280-day pregnancy.

2. One of the shortest recorded pregnancies where the infant survived was just 22 weeks. The baby had a number of complications but survived. An even younger baby, born at 21 weeks and 4 days, is now a toddler.

3. The oldest recorded woman to have a baby was 66 years old.

4. Blood volume in the body during pregnancy increases 40 to 50 percent. This increase helps with the extra oxygen needed to support a healthy pregnancy.

5. The uterus can expand greatly during pregnancy. During the first trimester, it’s about the size of an orange. By the third trimester, it expands to the size of a watermelon.

6. Moms-to-be can start producing breast milk just 14 weeks into their pregnancy.

7. Your voice can change during pregnancy. That’s because hormonal changes can cause your vocal folds to swell. It will most likely go back to normal after delivery or breastfeeding.

8. By the third trimester, a developing baby can recognize their mother’s voice from inside the womb.

9. About 1 in every 2,000 babies are born with teeth. These are loose natal teeth and sometimes need to be removed by a doctor. They can be painful for the mother during breastfeeding. They can also be dangerous — there’s a risk they may be dislodged and inhaled.

10. Many pregnant women in China avoid cold foods like ice cream and watermelon. They prefer hot drinks like tea and soup, believing that pregnancy is of a “cold” nature and that hot liquids help balance the yin and yang. There’s no evidence to support this claim, but this is still a common cultural practice.

11. In Japan, pregnant women can be issued a badge to put on a bag or hang on a necklace. The idea is that commuters on trains and buses will see the badge and offer their seats even when a woman is in early pregnancy and not yet noticeably showing.

12. Turkey has the highest percentage rate of babies born via cesarean section (50.4 per 100 live births), while Iceland has the lowest (15.2 per 100 live births).

13. As of 2015, 17.8 percent of pregnant women in France smoked into their third trimester. As a result, hospitals are starting to offer payment vouchers in exchange for participating in a smoking cessation program during pregnancy.

14. Eight — That’s the highest number of babies born alive to a single mother. In 2009, Nadya Suleman delivered her six boys and two girls in a California hospital.

15. There are more twins born in Benin than any other country, with 27.9 twins born per 1,000 births.

16. About 32 people out of every 1,000 is a twin. In the United States, the state with the highest percentages of twins are Connecticut, Massachusetts, and New Jersey. New Mexico has the lowest.

17. Opposite-sex twins (one boy and one girl) make up approximately one-third of twin births.

18. One in eight couples in the United States has trouble getting pregnant or sustaining a pregnancy.

19. Over seven million women in the United States receive infertility services in their lifetime.

20. In 2012, over 61,000 babies were conceived in the United States with the help of in vitro fertilization (IVF).

21. At age 30, a couple’s monthly chance of conception is around 20 percent. By age 40, the chance is around 5 percent each month.

22. The mean age of women having their first child in the United States rose from 24.9 in 2000 to 26.3 in 2014.

23. In 2015, 32 percent of babies born in the United States were delivered via cesarean section. There were 2,703,504 vaginal deliveries and 1,272,503 babies born by cesarean.

24. In the United States, the highest percentage of infants is born between 8 a.m. and noon each day. Less than 3 percent of infants are born between midnight and 6:59 a.m.

25. The United States ranks among the worst countries in the Western world for maternal death rate. There were an estimated 14 deaths per every 100,000 live births in 2015. Greece, Iceland, Poland, and Finland tied for the lowest rate at just three deaths per 100,000 live births in 2015.

26. There has been a rise in the number of water births in recent years. Just shy of 10 percent of all United States hospitals offer water immersion options for delivery.

27. Home births are also becoming more popular, but still the majority of women are delivering in a hospital or birth center. In 2012, 1.36 percent of births were at home, up from 1.26 percent in 2011.

28. Babies can cry in the womb. Researchers found expressions of displeasure in ultrasounds starting at just 28 weeks.

29. Pregnancy rates for teens (ages 15 to 19) in the United States are on the decline. There were more than 229,000 teen births in 2015. That was down 8 percent from 2014.

30. In 1879, the heaviest recorded baby was born, weighing in at 22 pounds. Sadly, he passed away 11 hours after delivery. Since then, healthy babies have been born in Italy and Brazil weighing 22 pounds, 8 ounces, and 16 pounds, 11.2 ounces, respectively.

5 myths

1. Myth: The shape of your belly can predict the gender of your baby.

The truth: Carrying low? Legend says you’re having a boy. If your belly is higher up, it’s a girl. Actually, stomach muscles stretch with subsequent pregnancies. So, if a woman’s belly is higher up, it probably just means she has strong abdominal muscles or it’s her first pregnancy.

2. Myth: The heart rate of a fetus can predict the gender.

The truth: Listen carefully to that heart rate and you’ll be able to tell the gender of your future baby, right? It’s not true. Normal fetal heart rate for all babies in utero ranges from 120 to 160 beats per minute. You’ll have to wait for the ultrasound or birth to find out the gender.

3. Myth: Your face shape and fullness during pregnancy can predict the gender.

The truth: You may have heard that if a woman has a full face or acne, she’s having a girl. This is false and another old wives’ tale. Your face shape and skin condition during pregnancy are influenced by a number of other factors, like diet and genetics.

4. Myth: Spice during pregnancy causes blindness in babies.

The truth: Eating spicy foods during pregnancy is perfectly safe but may lead to heartburn. Ask your doctor about a pregnancy-safe antacid if you are prone to indigestion while expecting.

5. Myth: Experiencing heartburn during pregnancy means your baby will be born with hair.

The truth: Actually, this one may have some truth. A small study found that women with mild to severe heartburn gave birth to babies with hair. Researchers think there may be a connection between pregnancy hormones relaxing both part of the lower esophagus and being responsible for fetal hair growth. But more research is needed.

The takeaway

There’s so much to learn about pregnancy and still many unknowns. If you are pregnant or plan on becoming pregnant, work with your doctor. They can help you come up with a plan for a healthy pregnancy and delivery and can answer any questions you have about symptoms, complications, and what to expect.