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Week 1 of Pregnancy: When Does It Start?

When you first start your pregnancy journey, you're filled with excitement as well as questions. When does week 1 of pregnancy start? What will be my due date? What sort of pregnancy symptoms-like light spotting or breast tenderness-should I look out for? Here's what to expect during your first pregnancy week.

What's the beginning of pregnancy week 1?

Pregnancy is calculated from the first day of your last menstrual period. Even though your little one has yet to be conceived in week 1, you’re already in the time window that is part of the 9 months of pregnancy. Conception usually occurs about 14 days after the start of your last menstrual period, and pregnancy gestation is usually about 40 weeks. The average pregnancy lasts between 37 and 42 weeks.

Once your period finishes, the inner lining of your uterus (endometrium) begins to thicken again in preparation for the implantation of a fertilised egg. If implantation does not take place, your progesterone levels fall, and your body gets rid of the thickened layer and the unfertilised egg. This is the bleeding we call a period.

If your menstrual cycles are regular, a missed period is an indication of a possible pregnancy. After the egg implantation is complete, a hormone called human chorionic gonadotropin (hCG) is released. Known as the pregnancy hormone, hCG helps nourish the pregnancy and tells your ovaries to stop releasing eggs. A pregnancy test is most accurate about a week after a missed menstrual period, when hCG levels are high enough to detect.

Your pregnancy at week 1: what’s happening inside

In your first week of pregnancy, your little one is still a single-cell egg in your ovaries. In the next week, if successful, the egg will be fertilised by a sperm. The fertilised egg will then make its way down your fallopian tube before implanting into the inner lining of your uterus to start growing over the next 9 months.

Conception happens when the egg and sperm unite in one of the fallopian tubes to form a one-celled entity called a zygote, which contains 46 chromosomes (23 from the mother and 23 from the father). These chromosomes will determine the genetic make-up of your child, and ultimately all their physical characteristics. The sex of your child is determined at fertilisation. If the egg receives an X chromosome from the sperm cell, your little one will be a girl. Receiving a Y chromosome means that your little one will be a boy.

While your child’s body can’t be measured 1 week in, your body is preparing itself and you can start working towards a healthy pregnancy by implementing healthy lifestyle habits.

Common pregnancy symptoms

During the first trimester, your body undergoes many changes that can result in pregnancy symptoms. However, there are no symptoms during the first week of pregnancy. Symptoms such as morning sickness and mood swings are in the cards for most women—but they won’t happen just yet. In fact, you won’t experience any early signs of pregnancy until a few weeks after conception. You may see some light spotting, but if heaver bleeding occurs, you should get medical advice from your doctor or healthcare providers. For now, make sure to take good-quality prenatal vitamins, pregnancy milk and folic acid to prevent neural tube defects.

Preparing yourself for week 1 of pregnancy

Before pregnancy symptoms present themselves, here are some things you can do and lifestyle changes you can make to ensure your body is healthy:

  • Start taking prenatal vitamins, especially ones containing folic acid
  • Start taking pregnancy milk, like Frisomum Gold
  • Track your menstrual cycle
  • Get plenty of sleep
  • Start exercising, with advice from your doctor or healthcare provider
  • Eat healthier foods
  • If you smoke, do quit
  • Reduce your caffeine intake
  • Find out about you and your partner’s family health history, and have a discussion with your doctor


As you start your journey into pregnancy-or even if you're still trying to conceive-it always helps to get health information from your doctor or healthcare provider. They will be able to give you expert advice and help you make sure that you're on the right track for a healthy pregnancy.



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