Quick Summary — Pregnancy Week 3 (1st Trimester) At 3 weeks pregnant, your baby is approximately the size of a poppy seed (0.1 mm, —) with 259 days remaining until your estimated due date.

🧒 Baby Development

Implantation! The blastocyst burrows into the uterine lining. The placenta and amniotic sac begin forming. Three layers of cells (ectoderm, mesoderm, endoderm) will become all organs.

🤰 What Mom Is Feeling

You might notice light spotting (implantation bleeding). Some women experience mild cramping or a slight temperature dip.

💡 Tips for This Week

Continue prenatal vitamins. Avoid hot tubs and saunas, which can raise core body temperature.

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