When Should You Start Taking Prenatal Vitamins?

Folic acid is a form of folate (vitamin B9). It is the only form of folate shown in studies to help prevent neural tube defects (NTDs) — serious birth defects of the brain (such as anencephaly) and spine (such as spina bifida).

Here is the timing problem that makes preconception folic acid so important: the neural tube forms and closes in the first few weeks of pregnancy, often before you even know you are pregnant. By the time a test turns positive, the window for prevention may already be closing. That is why the CDC's guidance is not "start when you find out" but "all women capable of becoming pregnant should get 400 mcg daily" — as a standing habit, the way you would take any daily vitamin.

The CDC also notes it is difficult to get the full 400 mcg from food alone, which is why a daily supplement matters even on a healthy diet. Our pregnancy dos and don'ts guide covers nutrition alongside this.

Do not take more than one multivitamin or prenatal per day, and do not mega-dose folic acid on your own — high intakes can mask a vitamin B12 deficiency. The standard 400 mcg is the evidence-backed amount for most people.

Use this checklist in the pharmacy aisle. A good prenatal is not about the fanciest brand — it is about these ingredients:

Side effects are common and manageable: nausea (take it with food or at bedtime), constipation (more fluids and fibre), and a metallic taste. If one brand bothers you, try another — the folic acid is what matters most, and gummies, tablets, and capsules all deliver it.

First: breathe. Nearly half of pregnancies are unplanned, and many people start folic acid only after the positive test. Starting now is still worthwhile. Begin a prenatal vitamin (or at least folic acid) as soon as you know you are pregnant, and tell your clinician at your first pregnancy appointment exactly when you started — they will factor it into your care plan and may discuss whether your situation calls for anything more.

You cannot rewind the clock, but you can give your body and your baby every advantage from today forward.

For most people, yes — a prenatal vitamin remains useful through the rest of pregnancy and often while breastfeeding. The reasons shift: after the neural-tube window closes, iron (for your expanding blood volume), iodine, vitamin D, and calcium keep doing important work. Many clinicians simply recommend staying on the same prenatal throughout. Ask your own provider what they advise — guidance can vary with your diet, bloodwork, and medical history.

A higher folic acid dose is a medical decision, not a DIY upgrade. Talk to your clinician before trying to conceive if any of these apply:

• You have had a previous pregnancy affected by a neural tube defect.
• You have diabetes, epilepsy, or take anti-seizure medication.
• You have a close family history of neural tube defects.
• You have had bariatric surgery or a condition affecting nutrient absorption.

In these cases a clinician may prescribe a much higher dose (commonly discussed is 4,000 mcg). This is prescription-only territory — do not scale up a standard supplement yourself. If you are just beginning your pregnancy journey, our first-time mom guide walks through the early steps.