Pregnancy Due Calculator
First Trimester 1 week pregnant

Pregnancy Week 1 - Menstrual Period & Pre-Conception

Week 1 of pregnancy is actually your menstrual period. Pregnancy is counted from the first day of your last menstrual period (LMP), even though conception has not yet occurred. This standard counting method means you are technically not pregnant during weeks 1 and 2.

Not yet conceived
Baby Size
N/A
Length
N/A
Weight
Week 1
of 42
Baby Development This Week

During week 1, there is no baby yet. Your body is shedding the uterine lining from the previous cycle and preparing for ovulation. Your uterus is getting ready for a potential pregnancy by building a new, nutrient-rich lining. Hormones are shifting as your body prepares to release an egg in the coming weeks.

Changes in Your Body

You are experiencing your menstrual period, which typically lasts 3 to 7 days. You may have cramping, bloating, and fatigue. Hormone levels are at their lowest point, and your body is beginning the process of developing new follicles in your ovaries that may contain this month's egg.

Common Symptoms at Week 1
Menstrual bleedingCrampingBloatingFatigueMood changes
Tips for Week 1
  • Start taking a prenatal vitamin with at least 400mcg of folic acid daily to prevent neural tube defects.
  • Schedule a pre-conception checkup with your healthcare provider to discuss your health history.
  • Begin tracking your menstrual cycle to identify your fertile window.
  • Avoid alcohol, smoking, and limit caffeine intake as you prepare for conception.
When to Call Your Doctor

If your period is unusually heavy, lasts longer than 7 days, or if you experience severe pain, contact your healthcare provider.

Frequently Asked Questions — Week 1

Explore Our Pregnancy Tools
Due Date Calculator
Conception Calculator
Ovulation Calculator
Week Calculator
All WeeksWeek 2