Dear Doctor,I am in my first trimester of pregnancy and can’t wait to find out the sex of my baby. I have been discouraged by my mother and aunties who say that it’s dangerous to go through a scan to find out the sex of the baby. The say it might have a negative effect on the baby. What should I do?Honorine Uwase 27,Kimisagara--------------------------------------------------Dear Honorine Uwase,Congratulations on your pregnancy, which I presume is your first. Actually, the sex of a baby is determined around the time of conception depending on whether it is a fusion of XX or XY chromosomes. Waiting 9 months to know the gender of a baby is the most pleasurable suspense for expectant parents. For about 10 years or so, antenatal ultrasound was considered safe for the baby.  It was done for several indications during pregnancy like knowing the gender of the unborn baby, gestational age, multiple pregnancies, screening for birth defects, foetal distress e.t.c.  During ultrasound examination, the foetus is exposed to very high frequency sound waves, which produce images of the baby on a screen and amplify the heart beats.No study so far has confirmed absolute safety of ultrasound and Doppler examinations on an unborn baby. It offers no extra benefit regarding continuation of pregnancy or outcome of pregnancy. In fact, except knowing the gender of the baby, all other information regarding the   in-utero baby can be obtained by a good clinical examination.Studies done on pregnant mice have shown that due to repeated ultrasound examinations, the new borns had low birth weight.  In laboratory experiments, ultrasound waves are known to cause chromosomal and cellular damage by producing internal heat.  Division and multiplication of cells is affected, which can potentially produce cellular hence organ defects. Nerve cells including brain cells are also at risk by ultrasound waves resulting in impairment of potential intellect development. They may damage testes affecting future fertility of male babies.Considering these potential risks of prenatal ultrasound, American Medical Association has cautioned against excess or unnecessary use of ultrasound during pregnancy. According to W.H.O., if there is no generally acknowledged benefit of ultrasound during pregnancy, there is no reason to expose the patient to increased cost and risks.In your case, you should heed to the advice of your elders. Be aware of the fact that a baby’s body is formed during the first trimester, followed by physical growth during the 2nd and 3rd trimesters. Hence, if possible, ultrasound can be avoided during the first trimester. Though not proven in human beings, theoretical risks do exist. If you are still very keen to know the sex of the baby, it is better to go for it after your first trimester.