Key Nutrients in Prenatal Vitamins, and What Happens If You Don't Get Enough

Folic Acid / Folate: Early‑Pregnancy Non‑Negotiable

Folate plays a crucial role in DNA synthesis and neural tube development, the formation of your baby's brain and spinal cord. Many guidelines reference 400–600 mcg per day during preconception and early pregnancy, though women should consult with their healthcare provider to ensure their nutrient needs are being met.

Low folate intake significantly increases the risk of neural tube defects such as spina bifida and anencephaly. Research also suggests possible higher risks of certain pregnancy complications and maternal anemia when folate levels are inadequate. For more on the differences between folate and folic acid, folate vs folic acid: what's the difference when you're TTC is a helpful read.

If you're not taking a prenatal, aim for 2–3 servings daily of folate-rich foods: leafy greens, beans, lentils, and fortified grains. Consider a separate folate or methylfolate supplement under provider guidance, especially if you're past week 4–6 of pregnancy.

Iron: Oxygen, Energy, and Anemia Risk

Iron supports red blood cell production and oxygen delivery to both you and your baby. Many guidelines reference 27 mg from all sources during pregnancy, though women should consult with their healthcare provider to ensure their nutrient needs are being met, significantly higher than non-pregnant recommendations because your blood volume increases by 30–50% during pregnancy.

Low iron intake or skipping prenatals increases your chance of iron-deficiency anemia, causing fatigue, dizziness, shortness of breath, paleness, and headaches. Research suggests significant iron deficiency may increase risks of preterm birth, low birth weight, and maternal complications during delivery.

If you can't tolerate iron-heavy prenatals, eat iron-rich foods daily: red meat, poultry, beans, lentils, and iron-fortified cereals. Pair plant-based iron with vitamin C (beans with citrus) and avoid tea or coffee around iron-rich meals. Ask your provider about gentler iron formulations, smaller divided doses, or iron labs to personalize your approach. Prenatal supplements with DHA often include gentle iron options to help meet your needs.

Vitamin D and Calcium: Bones, Immunity, and Mood

Calcium builds your baby's bones and teeth while protecting your bone density. Vitamin D helps absorb calcium and supports immunity and possibly mood stability. Most pregnant adults need about 1,000 mg calcium and at least 600 IU vitamin D daily, though some providers recommend higher vitamin D based on blood levels.

When these nutrients are low, your baby may draw from your stores, potentially impacting your bone health. Research suggests links between severe deficiencies and increased pregnancy complications, though individual outcomes vary significantly.

Without a prenatal, aim for three servings of calcium-rich foods daily: dairy, fortified plant milks, or leafy greens. Discuss vitamin D testing with your provider and spend 5–30 minutes in appropriate sunlight exposure several times weekly, as suitable for your skin tone.

DHA and Choline: Brain, Eyes, and Learning Potential

DHA, an omega-3 fatty acid, supports fetal brain, eye, and nervous system development. Choline works alongside folate for neural tube formation and cognitive development. Many prenatal vitamins contain minimal or no DHA and choline, making separate attention to these nutrients important.

Research associates low omega-3 and choline intake with suboptimal neurodevelopmental outcomes, though this represents potential risk rather than inevitable consequences. These nutrients remain crucial throughout pregnancy as your baby's brain grows rapidly.

If you're not taking comprehensive supplements, eat two servings of low-mercury fish weekly (salmon, sardines) totaling 8–12 ounces. Include choline-rich foods like eggs, lean meats, and soy products. Consider standalone DHA supplements, especially if you avoid fish.

Timing Matters: Before, During, and After Pregnancy

Before Conception: Why Prenatals Are Recommended 1–3 Months Ahead

Professional groups recommend starting prenatals at least one month before conception, with some suggesting up to three months. This timing matters because neural tube formation and early organ development occur within the first 28 days after conception, often before you know you're pregnant.

If you didn't take prenatals before conceiving, countless pregnancies still proceed beautifully. Risk doesn't equal certainty. Start a prenatal as soon as you know or suspect pregnancy, immediately boost folate-rich foods, and schedule early prenatal care to discuss any specific screening recommendations with your provider.

First Trimester: Nausea, Fear, and Missed Prenatals

Rapid organ development during the first trimester creates high demands for folate, B vitamins, and foundational nutrients. Unfortunately, nausea and vomiting often peak between weeks 6–12, making pills and strong smells difficult to tolerate.

When you can't keep prenatals down, nutrient gaps become more likely, especially for folate, B6, and iron. You may feel increased fatigue or dizziness. Try taking your prenatal with a small snack, switching to a gummy formulation, or dividing doses throughout the day.

Second and Third Trimester: What If You Stop or Never Start?

Your baby's brain and lungs undergo rapid development during the second and third trimesters, while your iron needs peak as blood volume increases by 30-50%. What happens if you don't take prenatal vitamins during this crucial period? You face a higher likelihood of iron-deficiency anemia and persistent fatigue that can impact your daily life and pregnancy experience.

When significant deficiencies develop, research suggests potential increased risks of low birth weight or preterm birth. However, it's never too late to course-correct with intentional nutrition support. For more information on the science behind prenatal vitamins and pregnancy, see this research on prenatal vitamins and pregnancy outcomes.

If you stopped taking prenatals in your second or third trimester, first identify why, was it side effects, cost concerns, or simple forgetfulness? Then take these practical steps: restart with a more tolerable formula featuring gentle iron or gummy options, prioritize iron-rich and nutrient-dense foods daily, and request blood work to check iron, vitamin D, and B12 levels so your support can be personalized to your actual needs. If you're considering different supplement forms, prenatal gummies vs pills: what's better for you & your baby can help you decide.

Postpartum and Breastfeeding: Continued Nutrient Demands

Nutrient needs remain elevated throughout the fourth trimester and beyond, especially during breastfeeding. Minerals and vitamins support milk composition, maternal recovery, mood stability, and energy levels when your body is working overtime.

Stopping prenatals immediately after birth increases your risk of postpartum depletion, that "wiped out" feeling characterized by fatigue, hair shedding, low iron, and difficulty bouncing back. Certain nutrient levels in breast milk may also be impacted when dietary intake consistently falls short. For a detailed look at what to expect after delivery, what happens during your first postpartum visit offers helpful insights.

Continue a postnatal or breastfeeding-specific vitamin for at least 3-6 months postpartum under provider guidance. Focus on hydration with 8-10 cups of water daily and balanced meals containing protein, healthy fats, and fiber at every eating occasion.

Can Healthy Diet Replace Prenatal Vitamins? Real-World Analysis

Whole foods provide fiber, phytonutrients, and balanced macronutrients that supplements cannot replicate. Prenatals are designed to complement a nutrient-dense diet, not replace it. The ideal approach prioritizes food first, always.

A strong dietary foundation includes 2-3 servings of fruit and 3+ servings of vegetables daily, three palm-sized protein portions, whole grains, and healthy fats from nuts, seeds, avocado, and olive oil.

Why Diet Alone Often Falls Short in Pregnancy

Real-world barriers frequently prevent optimal nutrition during pregnancy. Nausea and food aversions, limited access to fresh foods, busy schedules caring for other children, and financial constraints all impact dietary quality.

Certain nutrients prove particularly challenging to obtain in adequate amounts from food alone: folate at 400-600 mcg consistently, iron at 27 mg daily, and DHA plus choline if you don't regularly consume fish and eggs. For most women, a diet-plus-prenatal approach provides the most reliable protection against nutrient gaps. For more on the medical perspective, see this Cleveland Clinic guide to prenatal vitamins.

If You Choose Targeted Supplements Instead

Some women, in consultation with their providers, may choose individual supplements rather than a comprehensive prenatal. This approach requires careful coordination and medical oversight.

A targeted "food plus specific support" strategy typically includes: separate folate or methylfolate at 400-800 mcg per provider guidance, iron supplementation based on blood work results, fish oil or DHA supplement providing 200-300 mg DHA daily if not eating fish regularly, and vitamin D customized to blood levels.

These choices should always be made with healthcare provider guidance, self-directed megadoses can be unsafe for both mother and baby.

Real-Life Scenarios: Practical Solutions for Common Challenges

Forgot Prenatal for Days or Weeks

Short gaps usually do not cause immediate harm, risk develops from ongoing, long-term deficiencies rather than brief interruptions. Resume your normal schedule without doubling up unless directed by your provider.

Add extra nutrient-dense foods over the next 3-5 days: leafy greens, beans, eggs, and fortified cereals. If you've missed prenatals for more than 2-3 weeks, mention this at your next appointment and ask whether lab work is recommended.

Started After Positive Pregnancy Test

Many women only begin prenatals after confirming pregnancy, home tests often aren't taken until 4-5 weeks gestation. This timing is common and manageable with appropriate action.

Start a prenatal immediately and focus on folate-rich foods daily. Discuss timing with your provider, who may recommend additional folate or specific screening based on your individual situation. Remember that many healthy pregnancies begin this way.

Frequently Asked Questions

Is it too late to take prenatal vitamins at 20 weeks?

It’s never too late to start taking prenatal vitamins, even at 20 weeks. While early supplementation supports critical development in the first trimester, continuing prenatals throughout pregnancy helps meet your increased nutrient needs and supports your baby’s growth. We encourage you to talk with your healthcare provider to tailor the best plan for you and your little one.