The Nutrients That Matter Most in Your First Trimester

The first trimester gets a lot of attention for morning sickness, but nutritionally, it is one of the most important windows in your entire pregnancy. Several of the nutrients your baby needs most are required earliest, often before you even know you are pregnant.

Folate: the nutrient that can't wait

Folate's most critical window is the first 28 days after conception, the period during which the neural tube, which becomes the brain and spinal cord, closes.¹ This is why folic acid supplementation is recommended to begin before conception, not after a positive test.

The NHMRC recommends 600mcg of folate per day during pregnancy, nearly double the standard adult requirement.² Good food sources include leafy greens, legumes, and fortified bread and cereal, but supplementation is still recommended for most women because food alone rarely covers the full target.

Iodine: easy to miss, hard to recover from

Iodine is essential for thyroid hormone production, which directly drives your baby's brain development from the very first weeks. The World Health Organization and NHMRC both recommend 220 to 250mcg of iodine per day during pregnancy, up from 150mcg for non-pregnant adults.³

Iodine deficiency in early pregnancy has been linked to lower IQ outcomes in children, even in cases of mild deficiency.⁴ Because dietary iodine intake varies so widely depending on soil content and food processing, the NHMRC specifically recommends a 150mcg iodine supplement for all women who are pregnant, breastfeeding, or planning pregnancy, in addition to dietary sources.³

Iron: building blood volume early

Your blood volume begins expanding from early pregnancy to support the placenta and growing baby. Iron requirements rise to 27mg per day, and deficiency in the first trimester has been associated with increased risk of preterm birth.⁵ Pairing iron-rich foods with vitamin C, such as spinach with citrus, improves absorption meaningfully.

Vitamin D and calcium: building from week one

Bone mineralisation for your baby begins early, and both calcium and vitamin D requirements increase to support this. The NHMRC recommends 1,000mg of calcium per day during pregnancy.² Vitamin D also supports immune function for both mother and baby.

What this means in practice

If morning sickness makes eating difficult in these early weeks, prioritise small amounts of nutrient-dense foods over large meals. A single boiled egg, a slice of cheese, or a few crackers with peanut butter contribute meaningfully even when appetite is low.

This article is for general informational purposes only and does not constitute medical advice. Always consult your obstetrician, midwife, or registered dietitian for guidance specific to your pregnancy.