Pregnancy Week 1

Week 1 of pregnancy begins on the first day of your last period. That can sound odd, because you are not actually pregnant yet. In the standard 40-week pregnancy calendar, the first two weeks are counted before conception, because pregnancy is dated from your last menstrual period rather than the exact day sperm meets egg.

This system is used because most people can identify when their last period started more easily than the precise date of ovulation or conception. So, by the time you conceive, you may already be counted as around two weeks pregnant. A little head start, at least on paper.

During this week, your body is clearing the old uterine lining through your period. Soon, it will begin preparing a fresh lining, ready in case an egg is fertilised later in the cycle and implants.

There is no embryo yet, and no baby development to track this week. Instead, this is the start of the cycle that could lead to pregnancy.

At the start of Week 1, your period begins. The lining of your uterus breaks down and leaves your body as menstrual bleeding. This marks day one of your menstrual cycle.

Your hormone levels are also resetting. As your period continues, your body will start preparing another egg for ovulation later in the cycle. The lining of the uterus will then begin to rebuild, creating the right environment in case pregnancy happens.

You may feel just as you normally do during your period. That might include cramps, tiredness, bloating, headaches, mood changes, spots, breast tenderness, or changes in appetite. Some people have mild periods, while others find this part of the cycle physically and emotionally draining.

If your periods are very painful, extremely heavy, very irregular, or affecting your day-to-day life, it is worth speaking to your GP. You do not need to wait until you are pregnant to ask for support.

If you are trying to conceive, Week 1 may not feel like the beginning of pregnancy at all. It may feel like your period arriving, another cycle starting, or another month of waiting.

That can bring mixed emotions. You might feel hopeful and ready to try again. You might feel disappointed, frustrated, anxious, or tired of tracking dates. You might also feel completely calm and practical about it.

All of those reactions are understandable. Trying for a baby can become emotionally loaded very quickly, especially if it has taken longer than expected or if you have experienced loss before.

If tracking every sign and symptom is making you miserable, it is okay to step back a little. Some people find ovulation tests and apps helpful; others find them stressful. The best approach is the one that helps you feel informed without making your whole life revolve around your cycle.

If pregnancy is possible this cycle, Week 1 is a useful moment to set up the basics rather than overhaul your whole life. The NHS recommends taking 400 micrograms of folic acid every day before pregnancy and until 12 weeks, because it helps reduce the risk of neural tube defects such as spina bifida. Some people are advised to take a higher 5mg dose, including people with diabetes, some people taking anti-epilepsy medicines, and those with a personal or family history of neural tube defects, so check with a GP if you think this may apply to you.

Useful foundations this week:

Try not to turn Week 1 into a perfection project. Small, steady changes are more useful than panic-rewriting your whole routine in one go.