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Pregnancy weeks:

1 and 2 weeks pregnant: Symptoms and what to expect

The first week of pregnancy begins on the first day of your last period. If you get pregnant during this cycle, this is when your first month of pregnancy begins.

Weeks 1 & 2 of pregnancy: What to expect

If there’s any part of your pregnancy that’s going to fly by, it will be these first two weeks, during which you won’t know you’re pregnant at all.

Even if you think you know when it was, remember that sperm can live inside a woman’s body for up to 5 days, so it didn’t necessarily happen when you think it did!

Therefore, the first month of pregnancy (weeks 1 – 4) is made up of two weeks where you’re technically not pregnant, and then, usually, two weeks where you might start to notice the early signs of pregnancy.

Medical professionals count weeks 1 and 2 as the beginning of pregnancy for two reasons – first, because with each new menstrual cycle, your body is preparing to have a baby, and second because it is difficult to know when exactly conception took place.

Weeks 1 – 2: Preparing for ovulation

So, what’s going on inside in these first two weeks?

Your uterus is building a new lining and your ovaries are preparing to release an egg (maybe more than one!). Ovulation typically occurs 10-16 days before your period comes, so around the midpoint of an average 28-day cycle.

Conception, or fertilisation, therefore usually falls in week three of your pregnancy.

Signs of ovulation

Some people are very aware of their cycle and the signs of ovulation, whereas others find it difficult to keep track of their periods. If you are trying to conceive, you might take note of symptoms that suggest you’re ovulating, including:

  • Wetter, clearer and more slippery cervical mucus
  • A slightly elevated body temperature
  • Breast tenderness, bloating and tummy cramps – although these are not strong indicators of ovulation.

If you’re trying to keep track, ovulation predictor kits can provide help identifying the higher hormone levels that indicate ovulation.

Early signs and symptoms of pregnancy

Although there are no medical symptoms or signs of pregnancy immediately after fertilisation, women often have an instinct that tells them otherwise. You might notice a state of mind that you’ve never felt before, where you feel happy and satisfied as if you’d completed a major task. However, this alone is not a guaranteed sign of pregnancy.

Possible signs of pregnancy are generally divided into three categories.

If you notice these signs, there's a chance you may be pregnant:

  • Tiredness
  • Sore breasts
  • Nausea
  • A metallic taste in your mouth
  • Sharp abdominal pain


Once you notice these signs, you can almost certainly assume that you are pregnant:

  • You don’t get your period
  • Constant nausea
  • Sore breasts and sensitive nipples


Medical certainty is established by:

  • Detection of pregnancy hormone HCG in urine or in blood
  • Confirmation via an ultrasound scan performed by a doctor or sonographer


Individual symptoms from the first two lists of signs will not tell you for certain that you are pregnant, but they might lead you to suspect it. Only if you experience multiple symptoms at the same time will your suspicions grow, in which case a pregnancy test may be a good idea. Once you are certain you are pregnant, your due date can be calculated by using our Due Date Calculator.

Size of your baby in weeks 1 and 2

In weeks 1 and 2, there is still nothing to be seen of the embryo, as your child is initially known when they begin to develop in your womb.

It’s not until week 3 that a very small embryo may be visible in an ultrasound scan.

Your baby’s development

“Embryo” means an unborn offspring, and the term is used to describe the fertilised egg from week 4 of pregnancy. From around week 10, when all vital organs have formed, we stop referring to your child as an embryo and start using the word foetus instead.

You may well be using a pet name for the unborn baby in your tummy - Peanut or something cute like that - and that's great! We prefer to avoid medical terms like "embryo" or "foetus" as far as possible, so we'll talk instead about your baby/unborn child, etc.

The egg which has matured so that it can be fertilised by the male sperm is between 0.11 mm and 0.14 mm in size at this stage, which means it can’t be detected without using technology. It contains all your genetic information and is therefore a hugely important part of the developing embryo.

Pregnancy weeks 1-2 tips

Folic acid supplements

If you're hoping for a baby, or suspect you may be pregnant, it's wise to take folic acid supplements. In the first 12 weeks of pregnancy, your baby’s brain and spinal cord start to develop. Getting enough folic acid in this first trimester helps reduce the risk of problems occurring during this development, which might lead to conditions such as spina bifida. Eating foods rich in folic acid is also a good idea; here's a list of the top ways to get folic acid in your diet.

Talk to your GP about medication

If you're trying to conceive, talk to your doctor about any medications you're taking to ensure they are safe to take during pregnancy. It’s safe to take paracetamol during pregnancy, but aspirin and ibuprofen should only be taken under the advice by your doctor.

It’s time to stop smoking

If you smoke, the best thing you can do for the health of your baby – and yourself – is to give up as soon as you find out you are pregnant, or even earlier if you can. If your partner smokes, ask them to do the same, as second-hand smoke can also be dangerous.

For more information and help to stop smoking during pregnancy, you can speak to your GP, visit the NHS website, or contact the NHS Smoking Helpline on 0300 123 1044 (England only; Monday to Friday 9am to 8pm, Saturday and Sunday 11am to 4pm).

How early can home pregnancy tests show positive results?

Some home pregnancy tests can show positive results before your period is due, but typically the earlier you test before your missed period, the less accurate the results. For example, the ClearBlue digital tests can be used up to 5 days before your period is due, but the accuracy of the result is put at around 60% compared to 98% when used the day before your period is due.

For optimum results, wait until your period is due and take the test first thing in the morning when the urine is most concentrated.

If you’ve arrived on this page because a pregnancy test has told you you’re 1 – 2 weeks pregnant, congratulations!

But you can skip ahead, because those tests date from conception, and not from the first day of your last period. So, you are slightly further along than you think.

Use our due date calculator to work out when your baby is due.

Common questions in the first two weeks of pregnancy

What are the first signs of pregnancy?

As discussed, these first two weeks are not like the rest of your pregnancy – there aren’t really any signs or symptoms to be aware of, although you may notice the symptoms of ovulation.

In terms of what to look out for in the coming weeks, the obvious thing to look for is a missed period, as well as tender or sensitive breasts, fatigue and possibly nausea.

Confirm these symptoms with a pregnancy test.

Is diarrhoea a sign of pregnancy in the first week?

Diarrhoea is not a classic symptom of pregnancy, though for some women it does go hand in hand with abdominal cramps – as might be experienced during implantation – as well as the hormones associated with pregnancy and/or menstruation.

What should I avoid during the first 2 weeks of pregnancy?

Avoid smoking, alcohol, and too much caffeine. Talk to your doctor about any medications you’re taking that might be unsuitable to take during pregnancy.

Will a pregnancy test be positive at 1 week?

A pregnancy test could be positive one-week post-conception, depending on the pregnancy test you use and where conception falls within your cycle. Some pregnancy tests can give positive results up to 5 days before a missed period. However, the first week of pregnancy is counted from the first day of your last period, at which point the egg has not been fertilised and a test would not return a positive result.

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Information about the reviewer:

Marley Hall is a UK-registered, award-winning midwife, educator and author from Surrey. Qualified in 2009, Marley now works as a private independent midwife and is one of the founding members of NowBaby Live. She is a mother of 5 and is passionate about ensuring women and their partners are given informed choices. Find out more here.