First Trimester: What to Avoid in Early Pregnancy (2024)

The first trimester of pregnancy (the first three months) is when a fertilized egg divides rapidly into layers of cells and implants in the wall of the uterus. Those layers of cells become an embryo, and by six weeks, a heartbeat can be detected. By the end of the first trimester (the end of week 12) the baby’s bones, muscles, and organs have formed and it is now considered a fetus.

The baby grows fastest during the first trimester. By the end of the first trimester, the fetus can weigh about 0.5 to 1 ounce and measure an average of 3 to 4 inches in length.

The first trimester is also when pregnancy loss (miscarriage) can happen. This occurs in about 10% of pregnancies.

Because of the rapidly developing baby as well as the risk of miscarriage, during the first trimester women are advised to avoid a number of activities and foods.

• Avoid smoking and e-cigarettes
  • A woman shouldn’t smoke at any time during her pregnancy so once a woman finds out she is pregnant she should talk to her doctor about ways to quit the habit
  • Babies born to mothers who smoke are at increased risk for birth defects
  • E-cigarettes are also not safe during pregnancy because the nicotine can damage a developing baby’s brain and lungs
• Avoid alcohol
  • There is no amount of alcohol that is considered safe to drink during pregnancy
  • Drinking during the first trimester can cause birth defects, lead to miscarriage and stillbirth, and cause behavioral and intellectual disabilities known as Fetal Alcohol Spectrum Disorders (FASDs)
• Avoid raw or undercooked meat and eggs
  • Raw or undercooked meat and eggs carry the risk of contracting listeriosis and toxoplasmosis, which can lead to serious and life-threatening illnesses, severe birth defects, and miscarriage
• Avoid raw sprouts
  • These can contain E. coli and Salmonella
• Avoid certain seafood
  • Mackerel and tilefish have a high mercury content
• Avoid unpasteurized dairy products and unpasteurized juices
  • This includes soft cheeses such as feta, Brie, and goat cheese
  • These may contain bacteria such as listeria
• Avoid processed meats such as hot dogs and deli meats
  • These can also contain listeria
  • They also contain nitrates and nitrites
• Avoid too much caffeine
  • Some caffeine is ok: about 200 mg (2 cups of coffee)
  • Caffeine can cross the placenta and affect a baby’s heart rate
• Avoid gaining too much weight
  • Pregnant women do not have to “eat for two” during the first trimester (women usually need more calories during the second and third trimesters, but not necessarily during the first)
  • Women who gain too much weight during pregnancy put their child at greater risk for obesity later in life
• Avoid saunas, hot tubs, whirlpools, and steam rooms
  • These places put a pregnant woman at risk of overheating, dehydration, and fainting
  • A significant rise in the mother’s core temperature could affect her baby’s development, especially during the first trimester
  • Some research has found that the risk of miscarriage may double if a pregnant woman uses one of these during the first trimester
• Avoid massage and acupuncture
  • These therapies are generally safe during pregnancy but a pregnant woman’s abdomen should not be massaged during the first trimester
  • Acupuncture as well is generally safe during pregnancy, but certain acupuncture points should be avoided
  • Women seeking acupuncture should make sure the acupuncturist is trained in treating pregnant women
• Avoid cleaning the cat’s litter box
  • A parasite found in feline waste called Toxoplasma gondii can cause miscarriage or stillbirth, or serious problems in babies born with the parasite
• Avoid certain cleaning products
  • Check the labels of cleaning products to make sure there are no warnings for pregnant women
  • Some mothballs and toilet fresheners have a chemical called naphthalene that can damage blood cells
• Avoid fake tans
  • These are generally safe for use during pregnancy, but they can cause an allergic reaction
  • Hormone levels during pregnancy make the skin more sensitive and can make a woman more prone to allergic reactions
  • Do not use tanning pills or tanning injections

References

https://news.sanfordhealth.org/womens/dos-and-donts-during-first-trimester-pregnancy/
https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-first-trimester
https://www.acog.org/womens-health/faqs/early-pregnancy-loss
https://www.whattoexpect.com/pregnancy/top-10-things-you-need-to-know-about-the-first-trimester.aspx