BY: Leong Phei Phei

The first 12 weeks of pregnancy, commonly referred to as the first trimester, is a crucial and vulnerable period for mother and child.

Dr Tan Thiam Chye, an obstetrician and gynaecologist at KK Women's and Children's Hospital (KKH), says the first trimester carries the highest risk for two reasons.

"First, miscarriages occur most commonly in the first trimester. Second, this is the critical time when organogenesis occurs, that is, the formation of various organ systems of the foetus. At this stage, the foetal development is extremely sensitive to any potential teratogens such as certain drugs, radiation and excessive alcohol, which can result in malformations of the baby," he explains.

Teratogen refers to any agent that causes a structural abnormality following foetal exposure during pregnancy.

Fortunately, once foetal heartbeat is detected, usually seen on a transvaginal scan by six weeks and transabodominal scan by seven weeks, the chance of a spontaneous miscarriage reduces to about 5 per cent, says Dr Tan.

That said, what mothers do or fail to do could put their pregnancies at risk, say doctors. For instance, those who do not take adequate folic acid increase the risk of their babies developing neural tube defects (NTDs), specifically spina bifida, which is the incomplete development of the spinal cord or its coverings, and anencephaly, which refers to a developmental defect in the central nervous system resulting in the absence of skull and forebrain.

Dr Tan advises: "Folic acid supplementation of 1mg daily can prevent NTDs by 57 per cent while taking a 5mg tablet daily would reduce the risk by 85 per cent."

Mothers with a history of ectopic pregnancy, a condition where the pregnancy sac is located outside the womb, should be on high alert.

Dr Tony Tan, a consultant obstetrician and gynaecologist at Raffles Hospital, says: "As vaginal bleeding is a common symptom of miscarriage and ectopic pregnancy, it is important to seek medical attention when this symptom arises. Patients with a past history of ectopic pregnancy have a 10 to 15 per cent chance of it recurring.

"Such patients should get an ultrasound scan as early as six weeks to locate the pregnancy sac."

And those who keep pets such as cats should exercise caution. Dr Tan from KKH explains: "Cats may transmit toxoplasmosis, a parasitic infection that can cause premature delivery and serious malformations of baby and low birth rate. Transmission usually occurs from contact with feline faeces.

"Ask your doctor for a simple blood test to check if you are immune to toxoplasmosis, because if you are (immunised) by a previous infection, you are not likely to get infected again."

Whichever stage of the pregnancy you are now at, there are general guidelines to ensure that you carry your baby to full term: See your obstetrician regularly, avoid smoking and eat a healthy diet.

THE RIGHT CHOICE
Dr Tony Tan from Raffles Hospital (RH) and Dr Tan Thiam Chye from KK Women's and Children's Hospital (KKH) on dos and don'ts of motherhood:

Is caffeine absolutely not for pregnant women?
Dr Tan (KKH): Caffeine is a stimulant and a diuretic. Because caffeine is a stimulant, it increases your blood pressure and heart rate, both of which are not recommended during pregnancy. Caffeine also increases the frequency of urination. This causes a reduction in your body fluid levels and can lead to dehydration. Limit drinks containing caffeine to one cup per day if you crave one.

Should I give up sashimi during pregnancy?
Dr Tan (RH): There is no documented case of infection of the foetus resulting in structural abnormalities because of eating sashimi. There is, however, a theoretical risk of bacterial and parasitic infection in the intake of any raw food. My advice is to avoid any raw food in pregnancy.

Should I stop dyeing my hair once I am pregnant?
Dr Tan (RH): Low levels of hair dye can be absorbed through the skin after application, and the dye is passed out in the urine. This minimal amount is not thought to be enough to cause a problem for the baby. However, pregnant women who work with such products for more than 40 hours per week as cosmetologists have a slightly increased risk of miscarriage. As such, avoid dyeing hair in the first trimester.

This article was first published in Health & You, The Straits Times on July 2, 2008.