Well-meaning Facebook comments, Grandma’s sage advice and the latest pregnancy trends from mommy blogs can lead to (mis)information overload and anxiety for first-time moms. Long-held dos and don’ts for pregnant women persist, but what is fact and what is fiction?

Claim: A baby’s gender can be determined by the shape of mom’s belly.

False. While we appreciate the age-old notion that boys carry lower in the belly and girls carry high, this is unfortunately an old wives’ tale. These days the baby’s gender can often be determined during the routine second trimester ultrasound around 17 to 20 weeks into the pregnancy. If you want to keep your baby’s gender a surprise for delivery, make sure to share your wishes with the sonographer (ultrasound technician) before the exam begins. 

Claim: A bigger baby is a healthier baby, so pregnant women should eat for two.

False. Some babies are naturally bigger than others, but overly large babies can cause more complications at birth. Your doctor or midwife will be tracking your and your baby’s weight and recommending dietary habits to ensure you don’t gain too much weight. Women who were a normal weight prior to becoming pregnant only need an additional 300 calories and should gain on average 25 to 30 pounds. 

Claim: Pregnant women shouldn’t eat fish — period.

False. Fish is a terrific source of lean protein and healthy omega-3 fatty acids, but some types of fish contain higher levels of mercury, which in large amounts can be dangerous to a developing baby. Fish low in mercury, such as salmon and canned light tuna, is recommended two to three times a week, but avoid high-mercury species such as swordfish. Also, raw seafood, such as poke, sashimi and sushi, is not recommended during pregnancy due to the risk of foodborne illness.

Claim: Exercising while pregnant is dangerous for baby’s health.

False. While high-impact sports should be avoided, there’s no reason pregnant women can’t follow an exercise program into their ninth month. Light jogging, walking, yoga and swimming are great ways to stay in shape, though a doctor should be consulted if cramping or bleeding occur. Be sure to hydrate well before, during and after exercising.

Claim: Women should not get a flu shot while pregnant.

False. The American College of Obstetrics and Gynecology and the Centers for Disease Control and Prevention highly recommend pregnant women receive the flu vaccine. Pregnancy lowers the immune system’s ability to fight off infections, so moms-to-be and their babies are more vulnerable to complications if they get sick. Flu shots given to pregnant moms can also protect babies after they’re born. Just make sure to request the flu shot and not the nasal spray vaccine, which is made from a live virus and not meant for pregnant women. 

Pregnancy is a wonderful opportunity to focus on developing or maintaining a healthy lifestyle. Focus on eating well, keeping a light exercise regimen and enjoying this special time.

Dr. Mabel Wong is chief of obstetrics-gynecology and Linda Chong Tim is chief of midwifery services at Kaiser Permanente Hawaii.