As it turns out, mother doesn’t always know best. Yet when it comes to advice during pregnancy, many expectant women defer to other moms. In fact, a 2010 study conducted by researchers at Royal Holloway, University of London confirms this, revealing that pregnant and postnatal women often prioritize advice from female family members, pregnant friends, and experienced moms rather than solely relying on medical recommendations. 

The study by Professor Paula Nicolson and Dr. Rebekah Fox from the Department of Health and Social Care at Royal Holloway (published in the Journal of Health Psychology) investigated three recent generations of pregnancy experiences. They questioned women who gave birth in the 1970s, 1980s, and 2000s. During interviews, women expressed that they believed their mothers and grandmothers had their best interests in mind when providing them with advice. In fact, for the older women who participated in the study, guidance from their female relatives served as their primary source of information. They concluded that these women valued the wisdom and experience passed down through generations, considering it a reliable and trustworthy resource.

But how do you separate fact from fiction when it comes to pregnancy advice? How do you distinguish researched empirical evidence from one-off anecdotal evidence? Let’s take a look at five common beliefs and early pregnancy advice to sort out what’s an old wives tale and what’s backed by science.

What to Expect When You're Expecting (5th Edition Paperback) is your pregnancy explained and your pregnant body demystified, head (what to do about those headaches) to feet (why they’re so swollen), back (how to stop it from aching) to front (why you can’t tell a baby by mom’s bump). Filled with must-have information, practical advice, realistic insight, easy-to-use tips, and lots of reassurance, you’ll also find the very latest on prenatal screenings, which medications are safe, and the most current birthing options—from water birth to gentle c-sections.

Truth or Myth?

1. If you have a lot of heartburn while you’re pregnant, your baby will probably be born with lots of hair.

Answer: Possibly true; more research is needed

Though it definitely sounds like an old wives’ tale, there’s actually some truth to this one. In a 2006 study, researchers at Johns Hopkins Hospital in Baltimore uncovered a surprising relationship between hairy babies and heartburn during prenancy. In their study, 64 pregnant women were asked to rate the severity of their heartburn during pregnancy. Researchers then had independent coders assess the volume of newborn hair by examining two photographs of the infants' heads taken shortly after birth. 

The results: The majority of women (78%) experienced some level of heartburn during pregnancy. The severity of heartburn was not related to factors such as the sex of the fetus or maternal characteristics like parity, age, or weight. However, there was a significant and positive relationship between the severity of heartburn and the volume of newborn hair. Specifically, most women (23 out of 28) who reported moderate or severe heartburn gave birth to babies with average or above-average amounts of hair, while the majority of women (10 out of 12) who reported no heartburn had babies with less-than-average or no hair.

Contrary to what was expected, there seems to be a connection between the severity of heartburn during pregnancy and the amount of hair on newborns. Researchers suggested that this association is possibly due to a shared biological mechanism involving pregnancy hormones. These hormones play a dual role by both relaxing the lower esophageal sphincter, leading to heartburn, and influencing the growth of fetal hair.

2. If a woman's carrying low, it's a boy. If she's carrying high, it's a girl (or vice versa).

Answer: Myth

The position of your belly doesn't provide any clues about the gender of your baby, but it does reveal information about your abdominal muscles. When a woman carries her baby high, it suggests that her abdominal muscles are likely in good shape. Conversely, a low position of the baby bump may indicate lax muscles due to previous pregnancies, age, or a lower fitness level. Additionally, the positioning of your "baby belly" is influenced by your physical frame. Taller women tend to have longer torsos, resulting in narrower bellies, while shorter women may appear wider due to their shorter torsos.

3. If the fetal heart rate is under 140 beats per minute (BPM), it's a boy.

Answer: Myth

The fetal heart rate has no correlation with the sex of your baby, according to the Cleveland Clinic. Numerous studies have been conducted, and they consistently find no difference in fetal heart rates between male and female babies.

During your routine prenatal visits, your healthcare provider will measure your baby's heartbeat. Using ultrasound, the heart rate of your fetus can be measured as early as six to eight weeks into your pregnancy. On average, a fetal heart rate falls within the range of 110 to 160 beats per minute (bpm), and it fluctuates when the baby is active (some babies may have heart rates that are slower or faster than the average range). 

4. Long labor may be a sign of having a baby boy.

Answer: Possibly true; more research is needed

When it comes to old wives' tales surrounding pregnancy and labor, there is a possibility that one particular belief holds some truth: women expecting a boy may have a higher likelihood of requiring a cesarean section. Additionally, they might experience longer and more challenging labor. (It's important to note, though, that the risk of serious complications for the baby remains the same regardless of the baby's sex.)

It's crucial to clarify that these findings are based on limited studies and not definitive conclusions. Although some studies have shown these outcomes, the exact reasons behind them are not yet fully understood. One possible factor could be that, on average, boys tend to have a larger head circumference at birth compared to girls, which may present challenges when passing through the birth canal.

5. Eat a variety of veggies while you’re pregnant so that your baby will like them later.

Answer: True

This is not bad pregnancy advice and actually holds a lot of truth. The food and beverages you consume during pregnancy have the potential to flavor the amniotic fluid that the fetus starts swallowing in the second trimester. Research published by the American Journal of Clinical Nutrition shows that “consistent evidence indicates that flavors (alcohol, anise, carrot, garlic) originating from the maternal diet during pregnancy can transfer to and flavor amniotic fluid, and fetal flavor exposure increases acceptance of similarly flavored foods when re-exposed during infancy and potentially childhood.”

These flavors can also be transmitted through breast milk. A study published in Pediatrics found that infants between 4 and 8 months old, whose breastfeeding mothers consumed green beans, showed greater acceptance of the vegetable and consumed three times more of them compared to infants whose mothers did not have exposure to green beans. Furthermore, if you regularly consume bitter-tasting varieties like kale during pregnancy, your baby can develop a liking for them as well.

Conversely, it's important to note that the same principle also applies to unhealthy snacks. Recent research involving pregnant rats revealed that when their diets were high in sugar and fat, their offspring showed a greater tendency to become attracted to junk food, like cookies and chips, later in life.

The Bottom Line

Remember, some old wives’ tales about pregnancy may hold some truth, and some of them even seem to make logical sense. Perhaps the best course is to simply enjoy these old wives' tales with fondness and a smile, recognizing that they were based on oral traditions and inherited knowledge. It's understandable that their methods may not always align perfectly with modern science.

When reflecting on the past, it's important to remember that our belief in something often serves as the most powerful confirmation of its truth. If we anticipate something happening and it actually occurs, it doesn't usually feel like a mere coincidence. It feels extraordinary. And indeed, mama, you are extraordinary! Let these old wives' tales about pregnancy bring a smile to your face and broaden your perspective. Embrace them for the joy they bring and the added perspective they provide to your remarkable journey.

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