Fetal development: Weeks 1-4

If you’ve taken a test after missing a period you may be surprised to find out that officially you’re already several weeks pregnant, this is because doctors date a pregnancy from the first day of your last period, rather than from conception, which was probably around two weeks later.

So what’s happened so far?
From the moment your partner’s single sperm penetrates your egg somewhere along your fallopian tubes, a barrier membrane is formed around the egg, keeping out all the other sperm. The sperm and egg then fuse into one single cell, called the zygote, which immediately divides into two cells, then four, then eight and so on. This continually dividing and growing cluster of cells, now called the morula, is swept down inside the fallopian tubes towards the uterus. By the time the morula reaches your uterus, about four days after conception, it has grown to around 100 cells.

The bundle of cells then burrows its way into the lining of your uterus, which has thickened in preparation. The cells that now attach themselves to the walls of your uterus develop into the support system for your growing baby, the placenta, the other half of the bundle of cells will become the baby itself, and is now called the embryo. This process of implantation is usually completed by the end of week four of your pregnancy.

For most women this is around the time when they suspect that they may be pregnant, usually when a period is late. If you have some slight spotting around this time then it’s probably implantation bleeding, and nothing to worry about.

Most home pregnancy tests can give quite accurate results from when you first notice a late period, though there are also some early response tests that may be able to detect a pregnancy sooner. A visit to your doctor can confirm your pregnancy and kick start the process of visits and checks that will continue through pregnancy and into your new life with your baby.

What to do
If you think you are pregnant you can immediately start protecting the health of your baby and help to give him the best start in life by taking a few simple steps. As soon as you can start taking a folic acid supplement of 400mcg daily to assist the healthy development of the fetus. Talk to your doctor about any medication you are currently taking as well as any herbal or homeopathic treatments so you’re sure you’re not taking anything that may harm your developing child.

Smoking, drinking alcohol and taking recreational drugs during pregnancy have all been showed to be potentially damaging to the fetus and the first trimester is when your baby is most vulnerable, so you should try to cut out any of these. If you can’t kick an addiction then at least try to cut back as much as you can. If you thought ahead and did all this before conception then all the better, but if not, don’t beat yourself up about it now, just try and make the changes as soon as you can.

Be particularly careful when handling pets to avoid toxoplasmosis and start reading up on what foods you should avoid (or stock up on!).

Continue to get plenty of exercise to keep your body fit for pregnancy, but move away from high impact sports towards gentler forms of exercise like swimming and walking.

Your body
Some physical symptoms of pregnancy may develop in the first month of pregnancy as pregnancy hormones begin to flow through your body, so you may find you have sore breasts, are urinating frequently or have suddenly gone off coffee or alcohol. You may also begin to feel tired and emotional.

NB: All pregnancies are different and fetal growth rates vary, this is meant only as an approximate guide to development. If you have any concerns about your developing pregnancy then speak to your doctor.

Being prepared

Pregnancy symptoms - Being pregnant affects everyone differently, but there are a number of very common symptoms that you may experience in the early weeks.

The challenges of parenthood - In a few months time your life will be changing forever, are you ready to cope with the challenges?

Pregnancy for dads - It takes two to become pregnant and it can help to have two actively involved in the pregnancy, here's what you need to be ready for as a dad.

Caring for your pregnancy

Essential pregnancy dos and don'ts - Make sure you get your pregnancy off on a healthy track by following our essential pointers.

Taking folic acid - Besides cutting out toxins, the most important step you can take as a newly pregnant woman is to make sure that you're taking 400mcg of folic acid daily. Here's how and why.

Exercise during pregnancy - Not only is moderate exercise safe for most pregnant women, but it brings plenty of important benefits too, so here's the how and why of pregnancy exercise.

Pregnancy experiences

Time to conceive? - How long did it take you to conceive after you came off the pill? It's one thing reading all the percentages in the text books, but that's all a bit abstract so what about real experiences? What happened to us? asks Shoestring on the forum.

You can join in the discussions and share pregnancy experiences and advice with other ThinkBaby members in the pregnancy folder.

Telling your partner - I have to share this news. Now! But I don't want to call Martin at the office, I want to tell him to his face and he won't be home til he gets back from his business trip tomorrow at about 11pm. That means I have to keep this to myself for 36 whole hours! Barb tells us in her pregnancy blog.

If you want to record your pregnancy experiences why not start your own blog? You can share it with family and friends or print it out at a later date.

Other weeks