Week-by-week guide to your pregnancy

Weeks 0-4

Conception occurs 2 weeks after your last period. By week 4, the fertilised egg has implanted in the lining of your womb.

You will miss your period. You may notice a slight swelling or tenderness in your breasts.

Weeks 5-8
• The baby’s central nervous system begins to develop. The head is very large compared to the rest of the body.
• The baby develops from an embryo (about 2mm long) at week 5 to a fetus (about 15mm long) at about week 8.
• By week 6, the heart beat can be seen on ultrasound scan.

You may have confirmed your pregnancy with a urine pregnancy test by now. There is a sharp rise in hormonal levels to prepare you and your body for pregnancy and you may begin to suffer from nausea or vomiting.

Folate supplement is proven to reduce the incidence of brain and spinal cord abnormalities. As the central nervous system develops in early pregnancy, it is advisable to take folate supplements especially in the first 3 months of pregnancy.

Weeks 9-12
• By the end of week 12, all the limbs and most of the organs of your baby are formed.
• Your baby has ears, a nose and eyelids which are closed.
• Your baby moves around freely although you cannot feel any of these movements yet.

You may be visiting the toilet more often due to the increased pressure on your bladder from the developing fetus. It is advisable to have an ultrasound around week 12 of pregnancy as the due date can be most accurately estimated at this time. In addition, assessment of multiple pregnancies (if any) and First Trimester Screening (FTS) for Down Syndrome can be performed as well.

Weeks 19-24
• By around week 20, your baby will have his own set of fingerprints.
• Baby moves, kicks, swallows and even hears your voice.
• Baby will open his eyelids for the first time and start to sleep and wake in regular pattern.
• At the end of week 24, your baby is 30cm in length and weighs about 500grams.

Most mothers-to-be will feel fetal movements by week 20. Stretch marks may begin to appear on your tummy, breasts and thighs. Mother-to-be should avoid lying flat on their backs for long periods of time from this point onwards. A small pillow should be wedged under one side of the back during sleep.

It is advisable to have a fetal anomaly screening scan to assess the baby’s structure around week 18 to 21. The main purpose of this scan is to examine the structural anatomy of the fetus to check for major anomalies; paying special attention to the brain, face, spine, heart, lungs, stomach, bowel, kidneys, limbs, genitalia and umbilical cord.

Weeks 25-28
• Your baby is more active. As your baby swallows amniotic fluid, he may have hiccup which is often felt as a slight movement that is very regular lasting for a couple of minutes.
• Vernix will appear on the baby’s skin around 28 weeks. This white, fatty substance protects his skin like a waterproof coat, preventing it from becoming soggy in the amniotic fluid.
• At the end of week 28, the baby will measure about 40cm and weigh about 900grams.

Other people can now feel the baby moving inside you. Minor discomforts like leg cramps, heartburn, constipation and varicose veins may worsen.Women who are at risk of developing gestational diabetes (diabetes in pregnancy) are advised to have the oral glucose tolerance test at week 28.

Weeks 29-32
• The baby is now putting on fat and filling out. During the next 12 weeks, the weight will double.
• The skin, which had been wrinkly, begins to smooth out.
• By week 32, most babies would have turned upside down with their heads down (cephalic presentation).
• At the end of week 32, the baby is about 45cm and weighs about 1500grams.

You may suffer from breathlessness and heartburn as the womb continues to grow upwards. You may start to feel very tired again. You may occasionally feel your tummy going tight and hard; these are Braxton Hick’s contractions and are rehearsal contractions for labour. They may last up to a couple of minutes but are usually painless. It would be important for you to start monitoring fetal movements from now onwards. Generally, you should feel the baby move at least 10 times in 12 hours.

Weeks 33-36
• As your baby grows bigger, there is less and less room inside your womb for him to move around. In addition, due to the maturity of his brain, the previously frantic and erratic movements will seem more deliberate and purposeful.
• Your baby begins to move into the pelvis (engage) in readiness for delivery.
• At the end of week 36, your baby now measures 50cm and weighs about 2400grams.

Once your baby has engaged, you will usually feel more comfortable (lightening). However, after the baby’s head has engaged, there will be less room for your bladder so you will have to visit the bathroom frequently and often during the night. Your sleep pattern may be disturbed as it is more difficult to get comfortable at night.

Weeks 37-40
• Your baby is matured and is ready for delivery.
• Your baby’s growth may slow down towards week 40 when the placenta gets “older”.
• The average length of full-term babies is 51cm and the average weight is 3 to 3.5kg.

This is the time to make the final preparations for the arrival of the baby. Ensure your bags are packed and the nursery is ready. Always consult your doctor or check into the hospital if any of the following symptoms are experienced: (1) painful regular contractions that are between 45 to 60 seconds long, 5 minutes apart lasting more than one hour, (2) sudden gush of clear fluid from the birth passage, (3) heavy bleeding from the birth passage or (4) decrease fetal movements (less than 10 movements in 12 hours).

Incorporated in 2005, Singapore Medical Group (SMG) is a private specialist and primary healthcare provider with a network of more than 20 medical specialties. The Group is committed to its promise of providing patient centred medical care and experience to every individual. SMG has more than 27 clinics and a growing network of SMG Associates clinics all across the island.