You're already in your second month of pregnancy! By the time you reach 5 weeks gestation, you're probably already aware that there's a little life growing inside you. Chances are you've missed a period and taken a positive pregnancy test. But did you know that there are rare cases in which women reportedly have no idea they're pregnant until they give birth? Frightening!

Fortunately, most women do know that they're pregnant, and by week 5 you may be starting to really think about how this new family member is going to fit in with your current lifestyle. Where will the baby sleep? What stroller will you buy? When should you be baby-proofing the house? Remember to relax and take a breath, you have another 35 weeks until your little one is due to make an appearance.

Baby: What's Happening?

Week 5 of pregnancy is a huge week for your baby for a number of reasons. Firstly, the placenta is now firmly attached to your uterine wall, and becomes essentially a whole new organ (it doesn't stay forever though; it will detach and be delivered shortly after your baby arrives). Although the placenta is still developing, it's finally up and running as of this week, and provides oxygen and nourishment for your baby.

The placenta is also vital for a whole other reason, and that's to try and prevent any potentially harmful substances from reaching your baby, whether that be infection or, believe it or not, even your own blood.

15% of the population will have a rhesus negative blood type. If the father of your baby has a rhesus positive blood type, there's a 50% your baby will also be rhesus positive. So what's the problem? Quite simply, your body will see this foreign blood type as a threat, and try to rid of it.

But don't panic! The placenta does a great job of keeping your blood and your baby's blood separate, and shots are available for those women who have experienced bleeding or a fall which may have caused some blood to mix. The shot prevents any nasty side effects and some hospitals also offer preventative shots leading up to the birth.

The second big change this week is that your baby's heart begins to beat! Although you may not be able to hear it this early using a home doppler, an abdominal ultrasound at this time is capable of picking up the thump thump of that tiny heart. At this time, the heart rate will be much similar to yours, although it will become much faster in coming weeks.

Your baby will be busy this week, developing little stumps that will eventually become the arms and legs, and there'll be a lot of nerve growth as the brain and spinal cord become more and more formed. He or she is also growing at an alarming rate and is expected to almost double in size by the end of the week!

You: What's Happening?

Your hormones continue to rage, and you'll probably find this is both a good and bad thing. On one hand, you may find you've got heavy and constantly aching breasts as the milk ducts are stimulated to prepare for breastfeeding, and you might even be starting to experience morning sickness, caused by your body not being familiar with these high hormone levels.

On the other hand, there's that famous "pregnancy glow". Unfortunately, not everyone gets it, but for some, the change in hormone levels can create flawless skin, strong fingernails, and healthy and full hair (although beware that you'll likely experience hair loss after the birth!).

If you are burdened with all of the negative effects and none of the good, keep in mind that things usually calm down by the second trimester, and you should soon be feeling much like your old self.

As for your body, you probably won't look pregnant yet (after all, you've eaten food bigger than the size of your baby!), but there's plenty of changes going on. Did you know that when you're pregnant you have approximately 50% more blood running through your veins? This ensures the placenta has a good supply of oxygen for the baby. Your mucus plug will also be fully formed, creating a safety barrier at the opening of your cervix.

Handy Hints

The first trimester is when your baby is the most vulnerable, and three quarters of all miscarriages happen within these early months. Many women like to conceal their pregnancy until after the all important 12 week milestone, but if your job involves chemicals, overexertion, or if you work in a dangerous environment, you may want to have a quiet chat your boss so a risk assessment can be carried out.

As mentioned, the placenta does a fabulous job of keeping harmful substances away from your growing baby, but it's not a miracle worker. The placenta is unable to prevent alcohol, tobacco and other drugs from crossing over, and may not be able to stop the effects of severe food poisoning. It's recommended that any drug use is ceased, and you may want to watch out for risky foods, such as raw fish and cured meats.