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.

What happens during a pregnancy

The pregnancy will last for around 40 weeks or 10 months, during which time your child will steadily grow and receive everything they need to survive once outside your womb. After 38 to 42 weeks, a natural process will occur, which will lead to your child being born and separated from your body.

However, pregnancy isn’t just divided into weeks and months – we also talk about it in terms of trimesters, each of which lasts three months. This means a normal pregnancy is made up of three trimesters, with the last leading up to the birth. Weeks 1 to 13 form the first trimester, weeks 14 to 27 make up the second trimester, and the third trimester starts from week 28 and ends when your child is born.

Fertilisation: from ovulation to implantation

In week 1 (i.e. the first week of your new cycle), your monthly period starts. Each cycle begins with your period, which will be as long and intense as every other month.

All these processes are controlled by female hormones, which are aimed at enabling humans to reproduce and ensuring our survival as a species. As these processes are highly prone to failure, however, women who want to have a baby should be aware of a few things and try to ensure a level of calm within their daily lives.

In week 2, your eggs mature in your ovaries and the lining of your uterus gradually builds up again (the lining from your last cycle left your body during your last period). The lining needs to build up again so that the egg can be implanted in it once it has been fertilised. Women of childbearing age go through this process every month, even if they do not want to get pregnant – so if you don’t want to have a baby, being sensible and using contraception is extremely important.

You could think of it as “changing the sheets”: your body does everything it can to prepare in case your uterus needs to nurture a fertilised egg for a number of months. If you’re a woman who wants to get pregnant, you can also do your bit to help this process.

As menstruation progresses, the pain eases and your flow reduces until you can no longer see any blood.

At the end of the second week, around 14 days after menstruation begins, many women experience a stabbing pain on their left or right side or in the centre of their body (this pain is sometimes called mittelschmerz) during ovulation. If the pain is at either side, this simply tells you which ovary released the egg. The pain, which can be severe, is caused by a brief irritation of the abdominal membrane.

Preparing for pregnancy

The eggs that mature each month in order to be fertilised are prepared for this for three months before they are released from the ovary. This maturation can only happen if you have a stable hormone cycle and a healthy body – and this process requires fat in addition to hormones, vitamins and minerals. Thus a balanced diet containing sufficient good fats is crucial in order to produce an egg that can be fertilised.

Another key factor is a sensible lifestyle including a healthy balance between exertion and relaxation. This will keep your hormone levels stable and is the best way to boost your chances of having a baby, in addition to having sex regularly around the time of ovulation.

Noticing the first signs 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

If you notice these signs, it’s likely that you are pregnant:

Sensitive nipples and dark areolas
Regular nausea and vomiting
Consistently high temperature

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 established by:

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

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. The formula is simple: First day of your last period - 3 months + 1 year.

It can be calculated easier and quicker with the HiPP pregnancy 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 belly – 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.

Questions you may want to ask your doctor or midwife

Even before ovulation and before you know for certain that you’re pregnant, women who want to have a baby have endless questions. Your doctor or midwife can help you with your biggest concerns.

Midwives can confirm whether or not you are pregnant, register your pregnancy and carry out almost all the necessary check-ups, such as taking your blood pressure, measuring your weight, testing your urine and blood levels, determining the position and size of your baby, and checking for a healthy heartbeat. They can’t perform ultrasound scans, however – that’s a job for your doctor.

When is the best time for successful fertilisation?

If you’re familiar with what goes on in your body, you may well have noticed the symptoms that suggest you’re ovulating. You’ll still want to know exactly when is the right time to try to conceive.

There are a several ways of knowing with a high level of certainty when you’re ovulating. Each month your body prepares your uterus in case one of your eggs is fertilised, so that it can be implanted in the uterus wall.

Before that, an egg matures in one of your ovaries and is released between 14 and 17 days after the first day of your period, a process called ovulation.

One way to tell when exactly this occurs is to measure your temperature. A woman’s basal body temperature increases when she ovulates and remains higher than usual until ovulation is over, and you can measure this temperature using a special thermometer which goes to two decimal places.

An equally reliable method is to count the days after the first day of your period. Doing this as well as measuring your basal body temperature (which can be tracked as a curve) will help you know for certain when you’re ovulating.

You can also use our fertility calculator to quickly determine your fertile days.

Is it important to have sex before ovulation if want to get pregnant?

Yes! The best time to have sex is two days before ovulation. The pH levels in your vagina and the secretions of your cervix are ideal for allowing male sperm to pass through to the fallopian tube around the time you’re ovulating. Sperm can survive and be capable of fertilising an egg for around 48 hours after entering a woman’s body.

As you usually don’t know exactly when you’re ovulating, you “should” be having sex frequently during your fertile days if you want to increase your chances of getting pregnant – the more often the better. Interesting fact: even if a healthy, fertile couple have sex during the woman’s fertile days, the probability of getting pregnant is only 25%! So don’t be too disappointed if it doesn’t work first time. Many couples spend months trying before it happens.

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Information about the author:

Juliane Jacke-Gerlitz is a registered nurse. She has been working in the field of mother and breastfeeding counselling for more than ten years. Currently she is working as a medical writer and psychological consultant. Juliane Jacke-Gerlitz has been married for 22 years, is a mother of eight children and lives with her family in Halle.

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