Every mother- and father-to-be dreams of having a healthy baby. One of the first signs of baby’s health can be established by verifying whether or not it has a normal chromosome set and no organ abnormalities. To achieve this goal, antenatal ultrasound examinations (U/S) play the most important role. Also, preventing a preterm delivery and ensuring maternal health are essential. This involves taking care of chronic diseases, such as diabetes or hypertension, and determining which mothers have high-risk pregnancies (for example, identify those mothers likely to develop preeclampsia, which is pregnancy related high blood pressure and associated with kidney damage).
Nowadays, U/S examination is a major part of the routine antenatal follow-up and every couple should be offered a First Trimester U/S, with or without screening (biochemistry and measurement of nuchal translucency, etc.) and can accurately determine the estimated date of delivery. The earlier multiple pregnancies are detected, the better. If fetuses share a single placenta (monochorionic twin pregnancy), there is an increased risk for pregnancy complications when compared to fetuses with their own placenta. Therefore, monochorionic twin pregnancies should be followed by U/S every 2-3 weeks; other twin pregnancies can be examined every 4-6 weeks. Certain abnormalities can be identified at this early stage and genetic counseling given to parents. If parents want to know their risk for genetic problems, combining the U/S examination with the biochemistry allowing the identification of mothers at high risk for abnormal chromosomes or other pregnancy complications in up to 92-95% of cases.
After genetic counseling, invasive genetic testing can be offered (chorion villus sampling (11-14 weeks) or amniocentesis (15 weeks onwards). A detailed organ scan at 20-22 weeks completes the risk assessment. If U/S shows a normal intrauterine pregnancy and no soft markers for abnormal chromosomes, a sensitivity of up to 96% can be achieved for finding chromosomally abnormal babies without invasive testing. This is especially pertinent today when more and more prospective mothers are above 35 year of age. The risk of having a Down syndrome baby, for instance, increases with age. As an example, a 25 year old woman has a risk of 1:1352 (at 40 weeks) whereas at 35 years the risk is 1:356 and at 40 years 1:97. The doctors performing a First Trimester Screening should be certified by the Fetal Medicine Foundation.
Dr. Heli Spalding [MD, PhD] is a Consultant Obstetrician and Gynecologist and Specialist in Fetal Medicine at Royal Bahrain Hospital. For more information or to book your appointment, call 1724 6800 or plan your visit at www.royalbahrainhospital.com.