WEEK 1 / 40 · Trimester 1

Pregnancy Week 1

Preparation week

About 39 weeks until birth

The first weeks
  1. 1Preparation

Pregnancy is counted from the first day of your last period; there is no embryo yet in the first three weeks. The first size comparison starts in week 4.

Your body is laying the groundwork for pregnancy. Fertilization has not happened yet — this week marks the start of your last menstrual period.

What's Happening With Your Baby This Week?

  • Fertilization has not yet occurred; pregnancy weeks are counted from the first day of your last period.
  • Your uterine lining is renewing and follicles in your ovaries are maturing.
  • About 15-20 follicles begin developing in the ovaries, but only one will become dominant.
  • Estrogen levels start rising, causing the uterine lining (endometrium) to thicken.
  • Your body is laying the groundwork for pregnancy through progesterone and FSH hormones.

This Week's Tips for Mom

  • Starting a folic acid supplement would be wonderful; taking the dose your doctor recommends can help support your baby's nervous system development.
  • If you use alcohol or cigarettes, quitting now is one of the most valuable steps for both you and your baby.
  • You can transition to a balanced, nutrient-rich diet; focusing on foods rich in iron, calcium, and zinc is a great idea.
  • Establishing a regular sleep routine will be very beneficial; aim for 7-8 hours of sleep each night for hormonal balance.
  • To reduce stress, set aside time for relaxing activities like meditation, gentle yoga, or nature walks.
Tip of the day: Starting folic acid early supports your baby's nervous system development and can reduce the risk of neural tube defects like spina bifida by up to 70%. It's recommended to start this supplement from the moment you plan your pregnancy.
This content is for informational purposes only and is not a substitute for medical advice. Length and weight values are averages; every baby grows at their own pace.

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