Pregnancy lasts about 40 weeks, counting from the first day of your last normal period. The weeks are grouped into three trimesters. Find out what checkups are to be done with you and your baby in these three stages.
For many women, especially after 8 weeks gestation, sufficient information about the baby may be obtained with transabdominal ultrasound scan (經腹部超聲波掃描). Sometimes transvaginal ultrasound (經陰道超聲波掃描) may be required to get better and clearer images of the female pelvic organs including the developing pregnancy as the ultrasound probe lies closer to these organs.
Sometimes the results of a first trimester ultrasound scan may be inconclusive or uncertain, and need to be combined with mother’s clinical history and other tests (e.g. blood tests such as NIPT, NIFTY, T21, Chorionic Villous Sampling 絨毛膜活檢, Amniocentesis 羊膜穿刺術, etc.) for an overall assessment.
can be done when gestational age is beyond 10 weeks. It works by testing mother’s blood, which also contain small amount of fetal DNA, for increased amount of DNA from Chromosome 21. Besides detecting Down syndrome, it can also detect Edward syndrome (an extra copy of Chromosome 18), Patau syndrome (an extra copy of Chromosome 13) and Turner syndrome (only 1 copy of Sex Chromosome [X]) and other chromosomal disorders. There are different types of NIPT, such as NIFTY and T21 test.
involves getting a small sample of the placental tissue by a fine needle passing under ultrasound guidance through the mother’s tummy and her uterus to the placenta, where a small sample of tissue is obtained by suction. This procedure is an invasive one and carry a small miscarriage rate of 0.5-1% even conducted by experienced doctors. It is usually performed between 11-14 weeks of gestation.
involves withdrawing a small sample of amniotic fluid (羊水) from the mother’s uterus. Before the procedure, ultrasound scan is performed to locate the best site for sampling. During the procedure, a fine needle is passed through mother’s tummy into the amniotic cavity to withdraw a small amount of fluid. As amniotic fluid contains cells that the fetus has shed, it can be used for diagnosis. This is an invasive procedure carrying a small miscarriage rate of 0.5-1% even under experienced hands. It is usually performed between 16-20 weeks of gestation.
Fetal morphology ultrasound scan (胎兒結構性超聲波掃描), also called “structural scan” and “anomaly scan”, is usually performed during 18-22 weeks of gestation to examine the fetal structures in detail for the detection of congenital structural abnormalities (先天性結構異常) of the fetus.
Third trimester ultrasound is usually performed in the context of mother’s clinical history and the results of previous ultrasound scans (such as those areas covered in second trimester morphology scan) and investigations, specifically to follow up the well-being status of baby.
To conduct review on baby’s anatomy including size and well-being:
To check the baby’s heart rate and rhythm.
To review the position of the placenta, see whether there are concerns of a low-lying placenta (低位胎盤) or placenta praevia (前置胎盤) requiring intervention to prevent complications.
To assess the position of the baby, as this becomes more important when approaching delivery.