Pregnancy Week 1: The Starting Line

Nothing visible yet. Week 1 starts from the first day of the last menstrual period — conception hasn't happened yet. Your body is preparing by thickening the uterine lining and selecting the follicle that will release this month's egg.

Menstrual period is happening or just ended. Estrogen is rising as a follicle matures. Most women don't feel any pregnancy symptoms yet — because technically, pregnancy hasn't started. This is the baseline week that doctors count from.

• 01If you're reading this after a positive test, don't second-guess week 1 — it's counted from the first day of her last period, before conception even happened. Nothing you did or didn't do here changed a thing.
• 02The one thing that matters retroactively is folic acid. If she isn't already on a prenatal with at least 400 mcg, start one today — it protects the neural tube, which forms for real right around now.

If you're actively trying, this is a partnership from day one. Take vitamins together. Go to bed at the same time. Small solidarity gestures now build the muscle memory you'll need later.