Congratulations! Unlike weeks 1 and 2 of pregnancy, by week 3 you've actually made your baby! One strong little swimmer made its way through and you're now on the path to parenthood. It doesn't look much like a baby yet, though, appearing more like a tiny cluster of cells that will eventually divide up to form the fetus and the placenta. This little cluster is so small that it's not even known as a fetus or baby yet, instead being known as an embryo.

Week 3 is the beginning of what is widely known as the dreaded "2 week wait". It's the time between ovulation and the start of your next period when, even though you may have successfully conceived, many home pregnancy tests will be unable to detect the hormone changes.

If you've been actively trying to conceive, week 3 can be a nightmare! Are you pregnant? Aren't you pregnant? Argh! Many women start "symptom spotting" at this time, keeping a close eye on any changes in their bodies, although it's important to remember that pregnancy symptoms don't always appear so early on, and a lack of symptoms at this time doesn't necessarily mean you're out of the running this month.

Baby: What's Happening?

Although your baby is nothing more than a teeny tiny group of cells right now, it doesn't mean there isn't a lot going on! Those cells are doubling, tripling, quadrupling quicker than you can say "blastocyst multiplication". They need a lot of energy to work so hard, but there's no placenta to feed them just yet. Instead, your baby is getting everything it needs from the thickly lined walls of your uterus, where it has begun to find a nice spot in which to embed itself.

The cells know exactly what they need to do and are already in the process of forming your baby's most vital organs; the brain and the heart. An abdominal ultrasound won't show anything at this time, but keen-eyed sonographers may be able to detect the beginning of the implantation process through a vaginal ultrasound.

You: What's Happening?

You're very unlikely to know you're pregnant yet, but your body sure does! The part of the cell cluster that will become the placenta releases human chorionic gonadotropin (HCG) hormone which tells your body that there's a baby forming. This hormone prevents the release of follicle stimulating hormone (FSH) so that no more eggs will be matured and ovulation won't occur again, at least for another 9 months.

HCG also increases estrogen and progesterone levels which work together to ,maintain the thick uterine lining which has been building up since your last period. This lining is essential, as it gives the cells somewhere to embed themselves, and provides that all important early nourishment until the placenta is ready to take over. It's these hormones that contribute to those famous pregnancy mood swings!

Week 3 is when the amniotic sac begins to form. At just 3 weeks, this is mostly made up of just water. The watery bag protects the precious cells right the way up until labor, hopefully. The sac continues to grow with the baby, so by the time your waters "break" you may find there's quite a bit of it! But don't worry, in many cases, the breaking of the waters is simply an ongoing trickle, rather than the huge gush that's popular in the movies!

Although pregnancy symptoms this early are rare (and are quite likely to be psychological if you're symptom spotting!), you may find that you are experiencing some changes, although you might not associate them with pregnancy.

Very early pregnancy symptoms are similar to those of pre-menstrual syndrome, and so if you do notice some changes, you may just think it's because your "time of the month' is approaching. An increase in hormone levels can cause skin and hair to become greasier than usual, and your breasts may be a little tender and swollen.

Handy Hints

It may be difficult, but try to refrain from taking a pregnancy test during this time. The moment you conceive, your body starts to produce HCG hormone. This is the hormone that is picked up during urine-based pregnancy tests. In a healthy pregnancy, HCG levels tend to double every 3 days, and so are not usually high enough to be detected by a pregnancy test until at least 11 days after conception. You don't want a false negative!

Keep an eye out for some signs and symptoms, but do it for fun! Symptoms this early on are uncommon so don't get caught up in symptom spotting or get disappointed. Reliable pregnancy tests or an ultrasound are the only sure way to know if you're pregnant.

It may be best to limit smoking and drinking at this time, but use your common sense. The first trimester is when all the vital organs of your baby are formed, and it's when your baby is most vulnerable. If you haven't done so already, start taking folic acid, which has been found to have a number of health benefits for unborn babies.