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Patient Resource

Supplements and Medications in Pregnancy

A patient guide to timing, interactions, and safety through the perinatal period

Badge Key

With fatTake with fatty food
MorningEnergizing medication
BedtimeSedating medication
Empty stomachAvoid food nearby

Key Dates

  • Folic acid: Start 1+ month before conception
  • Low-dose aspirin (high-risk pregnancies): Start after week 12, ideally before week 16; continue until delivery unless your obstetric clinician says otherwise
  • Tdap vaccine: Weeks 27-36 of each pregnancy

01

Take with Food

These are absorbed better when taken with a meal that contains some fat.

What When Why
Prenatal Vitamins With dinner or fatty snack Fat helps absorb vitamins A, D, E, K; reduces nausea
Fat-Soluble Vitamins A, D, E, K With fat-containing foods Fat improves absorption of these vitamins
Zuranolone Postpartum depression Evening meal with fatty foods Food with fat increases absorption. It causes drowsiness: do not drive or do anything that needs full alertness for at least 12 hours after each dose, for the whole course, even if you feel alert.
Omega-3 Fatty Acids With meals Supports baby's brain and eye development

02

Best Time of Day

Some medications are often taken at a certain time of day because of how they can affect energy and sleep. These are common patterns, not rules; your prescription label comes first.

What When Why
Activating antidepressants Fluoxetine, sertraline, bupropion Often morning Can be energizing for some people, and morning dosing can reduce trouble sleeping. Sertraline can be taken morning or evening.
Sedating antidepressants Mirtazapine, fluvoxamine Often bedtime These can cause drowsiness, and bedtime dosing puts it overnight. Higher fluvoxamine doses are often split into two.
Sedating antipsychotics Quetiapine, olanzapine Often evening or bedtime Evening dosing can reduce daytime drowsiness. Some schedules are split through the day; follow your prescription.
Prenatal vitamins If queasy Before bedtime May make nausea from the prenatal easier to tolerate; a little food with it can help too
Vitamin B6 For nausea As directed Vitamin B6 can help pregnancy nausea. A prescription delayed-release option combines it with doxylamine. Ask your obstetric clinician how much to take.
Magnesium As directed Sometimes used for leg cramps; the trial evidence is unclear. Ask your obstetric clinician before adding it.
Lithium* As prescribed Schedules vary and often change during pregnancy. Follow your own schedule; see the lithium page.
Low-dose aspirin High-risk pregnancies Once daily, as directed Consistent daily dosing matters for prevention. Your obstetric clinician sets the start and stop dates.
Progestin-only pills After delivery Same time every day Timing matters for effectiveness. If a pill is 3 or more hours late, use a backup method for the next 48 hours.

*Lithium schedules differ from person to person, and the dose is usually adjusted during pregnancy and again after delivery. Always follow your prescriber's instructions and keep your scheduled blood level checks; the blood is usually drawn about 12 hours after your last dose.

03

Specific Timing During Pregnancy

Some medications and supplements need to be started at specific points in your pregnancy. Your obstetric clinician decides whether each of these applies to you and sets the dates, and the same goes for the glucose test in the next section.

What When to Start Why
Folic Acid 1+ month before conception Prevents neural tube defects; critical in early weeks
Vitamin D Throughout pregnancy Supports your baby's bone growth. Whether extra vitamin D lowers preeclampsia risk is still unsettled.
Low-dose Aspirin Weeks 12-28, ideally before 16 Reduces preeclampsia risk in high-risk pregnancies. Continue until delivery unless your obstetric clinician gives you a different stop date.
Antiviral (for herpes) Recurrent genital herpes Starting at week 36 Lowers the chance of an active lesion during labor; it does not remove the risk entirely.
Tdap Vaccine Weeks 27-36 each pregnancy Passes immunity to your baby before birth

04

Empty Stomach and Fasting

Some medications and tests work best, or only work, without food beforehand.

What When Why
Iron* Empty stomach if tolerated Absorbed best without food, but gentler on the stomach with a little food. Vitamin C can help absorption. More on the iron page.
Glucose Tolerance Test Fasting overnight (3-hour test) Required for the 3-hour test. The first screening test does not need fasting.

*If iron causes stomach upset on an empty stomach, take it with a small amount of food. Food can reduce absorption, but tolerability matters for consistent use.

05

Spacing Between Supplements

Some supplements can reduce each other's absorption when taken together.

  • Iron + Calcium, Antacids (Tums), or Milk

    Keep them at least 2 hours apart; they can reduce how much iron you absorb. High-fiber foods can do the same, so take iron at a different time. See the iron page.

  • Calcium

    If you take a calcium supplement, split it into smaller amounts through the day; it is absorbed better that way.

  • MAOIs + Other Antidepressants

    Wait at least 14 days when switching (5 weeks after stopping fluoxetine). Your prescriber sets the plan.

06

Pairings to Avoid

Coffee or Tea + Iron

Can reduce iron absorption

Have them at a different time than your iron

Tea + Folic Acid

Green or black tea taken with folic acid may lower how much you absorb

Take your prenatal at a different time than tea

Alcohol + Breastfeeding

Passes into breast milk. Not drinking is safest.

If you drink, wait at least 2 hours per standard drink before nursing

07

Important Safety Cautions

These warnings can prevent serious problems during pregnancy.

  • Vitamin A: Do not take extra beyond your prenatal

    Too much preformed vitamin A can cause birth defects. Extra vitamin D is a separate question: add it only if your clinician recommends it.

  • Protein Supplements: Prefer whole foods; check ingredients

    Powders may contain herbs that are not studied in pregnancy. Have your obstetric clinician review the label.

  • Herbal Labor Remedies: Avoid castor oil, black cohosh, and similar

    Unpredictable effects; never use without medical supervision.

  • Unpasteurized Foods and Deli Meats: Avoid raw dairy; heat deli meats until steaming hot

    More likely than other foods to carry Listeria, which can cross the placenta and cause fetal loss.

  • High-Mercury Fish: Avoid shark, swordfish, king mackerel, tilefish (Gulf of Mexico), bigeye tuna, marlin, orange roughy

    Mercury causes neurologic problems in developing babies.

  • Methadone/Buprenorphine: Continue through pregnancy and labor; your team may adjust or split doses

    Prevents withdrawal; your treating clinician guides dosing, and your baby is monitored after birth.

*FDA/EPA fish advisory list. For complete guidance, see the FDA fish advice page.

Summary

Quick Tips to Remember

  • Take prenatal vitamins with dinner or at bedtime if you feel queasy.
  • Pair iron with vitamin C (orange juice) to help absorption.
  • Keep iron and calcium at least 2 hours apart.
  • Energizing meds are often taken in the morning and sedating ones at bedtime; follow your prescription label.
  • Start folic acid at least 1 month before trying to conceive.
  • Avoid extra vitamin A beyond what is in your prenatal, and add vitamin D only if your clinician recommends it.
  • Take your prenatal vitamin at a different time than green or black tea.
  • If you miss a dose, follow that medicine's own instructions or ask your pharmacist. There is no single catch-up rule, and some medicines should not be made up at all.

References

Medication information is provided for educational purposes only. Everyone responds differently to medications. Do not start, stop, or change medications without consulting your clinician.