Patient Resource
Supplements and Medications in Pregnancy
A patient guide to timing, interactions, and safety through the perinatal period
Badge Key
Key Dates
- Folic acid: Start 1+ month before conception
- Low-dose aspirin: Begin week 12, stop week 36
- Tdap vaccine: Weeks 27-36 of each pregnancy
1. Take with Food for Best Results
These work better when taken with a meal containing healthy fats.
| 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 | These vitamins need fat to be absorbed properly |
| Zuranolone Postpartum depression | Evening meal with fatty foods | Fat is essential for absorption; evening timing helps with drowsiness |
| Omega-3 Fatty Acids | With meals (200-300 mg daily) | Supports baby's brain and eye development |
2. Best Time of Day
Some medications work better at certain times based on how they affect your energy and sleep.
| What | When | Why |
|---|---|---|
| Activating antidepressants Fluoxetine, sertraline, bupropion | Morning | Can be energizing; prevents sleep problems |
| Sedating antidepressants Mirtazapine, fluvoxamine | Bedtime | These cause drowsiness; helps with sleep |
| Sedating antipsychotics Quetiapine, olanzapine | Evening or bedtime | Helps with sleep; avoids daytime drowsiness |
| Prenatal vitamins If queasy | Before bedtime | Sleep through any nausea; great for morning sickness |
| Vitamin B6 For nausea | As directed | Slow-release formula helps reduce morning sickness |
| Magnesium | Before bedtime | Natural muscle relaxant; prevents leg cramps |
| Lithium* | Once daily, usually evening | Simpler schedule; may be easier on kidneys. Your clinician will guide timing. |
| Low-dose aspirin | Once daily, weeks 12-36 | Consistent daily dosing is critical for prevention |
| Progestin-only pills | Same time daily (within 1 hour) | Precise timing required for effectiveness |
*Lithium dosing recommendations are evolving. Some formulations may still use divided dosing. Always follow your prescriber's instructions and attend scheduled blood level monitoring.
3. Specific Timing During Pregnancy
Some medications and supplements need to be started at specific points in your pregnancy.
| What | When to Start | Why |
|---|---|---|
| Folic Acid | 1+ month before conception | Prevents neural tube defects; critical in early weeks |
| Vitamin D | 600-4,000 IU daily throughout | Supports baby's bone growth; reduces preeclampsia risk |
| Low-dose Aspirin | Weeks 12-16; stop at week 36 | Reduces preeclampsia risk in high-risk pregnancies |
| Antiviral (for herpes) | Starting at week 36 | Lowers risk of active lesion during labor |
| Tdap Vaccine | Weeks 27-36 each pregnancy | Passes immunity to your baby before birth |
4. Take on an Empty Stomach
Some medications require avoiding food for proper absorption.
| What | When | Why |
|---|---|---|
| Iron* | 30-60 min before eating | Empty stomach gives best absorption; vitamin C boosts 2-3x |
| Glucose Tolerance Test | Fasting overnight (3-hour test) | Required for accurate gestational diabetes screening |
| Brexanolone infusion | 60-hour hospital stay | Breastfeeding can continue; separate caregiver required |
*If iron causes stomach upset on an empty stomach, take it with a small amount of food. Absorption will be slightly reduced but tolerability is more important for consistent use.
5. Spacing Between Supplements
Some supplements block each other's absorption when taken together.
- Iron + Calcium
Space by at least 2 hours. They compete for absorption.
- Iron + Antacids (Tums)
Antacids block iron absorption. Take separately.
- Iron + High-Fiber Foods
Fiber can block iron absorption. Don't take together.
- Calcium
Take 500 mg twice daily (not all at once) for better absorption.
- MAOIs + Other Antidepressants
Wait 14 days when switching (5 weeks for fluoxetine).
6. Pairings to Avoid
Coffee or Tea + Iron
Can reduce non-heme iron absorption
Green Tea + Folic Acid
Decreases folic acid effectiveness
Soda + Calcium
Phosphoric acid lowers calcium absorption
Alcohol + Breastfeeding
Passes into breast milk
7. Important Safety Cautions
These warnings can prevent serious problems during pregnancy.
- Vitamins A & D: Do not take extra beyond your prenatal
Excessive doses can be toxic to your baby.
- Protein Supplements: Prefer whole foods; check ingredients
Powders may contain herbs or sweeteners unsafe in pregnancy.
- Herbal Labor Remedies: Avoid castor oil, black cohosh, and similar
Unpredictable effects; never use without medical supervision.
- Unpasteurized Foods: Avoid raw dairy and deli meats
High Listeria risk; can cross placenta and cause fetal loss.
- High-Mercury Fish: Avoid shark, swordfish, king mackerel, tilefish, bigeye tuna,
marlin, orange roughy
Mercury causes neurologic problems in developing babies.
- Methadone/Buprenorphine: Continue during labor; doses may be split
Prevents withdrawal; your clinician will guide dosing.
*FDA/EPA fish advisory list. For complete guidance, see the FDA fish advice page.
Quick Tips to Remember
- Take prenatal vitamins with dinner or at bedtime if you feel queasy.
- Pair iron with vitamin C (orange juice) for 2-3x better absorption.
- Keep iron and calcium at least 2 hours apart.
- Take energizing meds in the morning; sedating ones at bedtime.
- Start folic acid at least 1 month before trying to conceive.
- Avoid extra vitamins A & D beyond what is in your prenatal.
- Skip green tea around the time you take your prenatal vitamin.
- If you forget a dose, take it when you remember unless it is almost time for the next one.
Medication information is provided for educational purposes only. Everyone responds differently to medications. Do not start, stop, or change medications without consulting your clinician.