First Week of Pregnancy | Symptoms and Signs

First Week of Pregnancy

In your first week of pregnancy, you’re actually not pregnant yet! In fact, your period has just started. This is because week one of pregnancy begins on the first day of your menstrual cycle. Even though your baby has not yet been conceived, it is still classed as part of the nine months of pregnancy.

So why is it called the first week of pregnancy?

Pregnancy is dated from the first day of your last menstrual period so that doctors can work out an estimated due date. Conception usually occurs around 14 days after the start of your period. Pregnancy gestation is usually around 40 weeks.

We don’t know exactly how long it takes each woman to grow her baby, but the normal length is between 37 and 42 weeks. This means your due date is really a guess date!

Did you know only 3-5% of babies are born on their ‘due’ date? Having a due date can place a lot of pressure on you (and your baby) to be born at a certain time, which is the last thing you need. It can be a good idea to think in terms of a ‘due month’ or assume you will be pregnant at 42 weeks to avoid excessive anticipation. There is one person who knows when your baby will be born – and that’s your baby. Your baby will come when he or she is ready.

If you’d like to work out your baby’s approximate due date, try BellyBelly’s due date calculator.

First Week of Pregnancy – Your Body

So let’s take a look at what’s happening to your body during the first week of pregnancy.

Once your period finishes, your endometrium (the inner lining of your uterus), begins thickening in preparation for implantation of a fertilized ovum. This thickening is caused primarily by an increase in the hormone progesterone. If implantation does not take place, progesterone levels falls and your body gets rid of this thickened layer causing bleeding. You get your period.

First Week of Pregnancy – Your Baby

In the first week of pregnancy, your baby is still a small, single celled egg, hiding in one of your ovaries. This egg is called an ovum and is only just visible to the naked eye. It’s completely unaware of what’s about to occur!

First Week of Pregnancy – For The Men

Listen up men — there are a few things you can do to help increase your chances of conception in the next week or two.

Cutting back on caffeine, alcohol, smoking and unhealthy, processed foods can have a positive impact on your health and fertility. Here are some other things you may not know about that can give you a boost right now:

  • Stress can interfere with sperm production. Get plenty of sleep and try some relaxation techniques like massage or acupressure to help relieve stress.
  • Studies have shown that men who eat soy foods may have a lower sperm concentration than men who don’t eat soy foods. Avoid soy!
  • Another study published in Fertility and Sterility showed that your mobile phone may also affect your fertility. They found that men who used a hands-free device with a cell phone and kept their phone close to their testicles had impaired sperm quality.
  • Tight fitting underwear or environments where overheating can occur — like a hot spa — can also impact on sperm production.
  • While not necessary to guarantee conception, the female orgasm can certainly improve the chances of a fertilized ovum implanting successfully. This article talks you through the how and why. Maintaining intimacy and connection while planning to conceive is important.
Last Updated: August 14, 2015


Kelly Winder is the creator of, a doula, writer and mother to three awesome children. Currently, she's travelling the world for 12 months with her partner and children, and hopes to inspire more families to do the same. Visit for more information.

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