Your Weekly Pregnancy Development: Week 1

The countdown to birth begins at the start of your last menstrual period

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The start of your pregnancy begins before conception

Week 1: Understanding the differences between gestational and fetal age

The 1st week of pregnancy is called preconception, because it actually begins with the start of your last menstrual period. Why? It's hard to pinpoint exactly when your egg becomes fertilized, but the date of your last cycle is a more accurate starting point.Your doctor will calculate your due date by counting 40 weeks from the start of your last menstrual period. 

This is called the gestational age, and it's how most doctors measure pregnancies. Because ovulation and conception take place about two weeks after your period begins, your baby's fetal age (which begins when your egg is fertilized) will be two weeks less than his gestational age. So, when you're 8 weeks pregnant, your baby's fetal age is 6 weeks.



prenatal vitamins

Your Week 1 nutrition and health

Early pregnancy nutrition tips

During preconception, your body is preparing for your baby. In fact, during every period, your uterus has shed its lining. This creates a new lining that's rich in blood vessels to house and nourish a developing baby. Now it's setting the stage for your pregnancy.

You can take action right now to make sure your body has the nutrition and exercise it needs and that is best for your baby in the months to come. During preconception, here are some guidelines to follow:

  • Be sure to eat balanced breakfasts, lunches, snacks, and dinners.
  • To gauge just how balanced your diet is, try writing down your meals and snacks for a week. Then, compare what you're eating to what is recommended on ChooseMyPlate.gov.
  • Supplement your balanced diet with prenatal multivitamins that include folic acid and other essential minerals and vitamins needed for pregnancy. Folate is found naturally in lentils, dried beans, and peas. Folic acid is added to fortified whole-grain breads. Talk with your OB/GYN about prenatal vitamins if you haven't already.
  • Address any medical conditions. If you're taking prescription medications, you should consult your doctor or OB/GYN prior to becoming pregnant.
Keep a close eye on the calendar
Be sure to mark on your calendar the day your menstrual cycle started, so you can tell your doctor at your first visit. Your doctor will use this to calculate your due date.
Pregnancy Weeks images

Exercising during your pregnancy


Pregnancy puts extra physical demands on your body. So being physically fit beforehand can help get you and your baby off to a good start.

When you're 1 week pregnant, and throughout your pregnancy, a balanced exercise program might be as important as a balanced diet. Here are some different types of workouts to consider:

  • Cardiovascular or aerobic exercise
  • Muscular endurance
  • Muscular strength or resistance training
  • Flexibility exercises

Note that focusing on muscles in your lower back and stomach is particularly good when preparing for pregnancy. However, be sure to check with your doctor before beginning any new exercise routine.

Keep learning about your baby's development every week
 
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