In clinical practice, we often see pregnant mothers produce a pile of ultrasound reports whenever they talk about pregnancy checkups, thinking that having an ultrasound will ensure the health of the fetus. In fact, this is a misconception. Pregnancy checkups are not only ultrasound, but also include routine prenatal checkups every 4 weeks or even every 1~2 weeks, blood and urine tests, Down’s syndrome screening, diabetes screening, thyroid function tests, etc. So, how many ultrasounds are needed during pregnancy? Can ultrasound reveal all abnormalities? Dong Xiaoqiu, director of ultrasound department of our hospital, helped pregnant mothers with the following explanation. At least 5 ultrasounds during pregnancy In daily outpatient clinics, we often encounter many mothers-to-be who have never had systematic prenatal ultrasound examinations and only remember to see if their babies are normal in the middle and late stages of pregnancy, which is one of the important factors for the high rate of neonatal malformations in China. Pregnant women should receive about five ultrasound examinations throughout their pregnancy. The first examination is at the beginning of the pregnancy, 6 to 8 weeks after menopause to determine if the pregnancy is present, if the fetus is alive and if it is an intrauterine or ectopic pregnancy. The second time is between 10 and 14 weeks of pregnancy, and is mainly to determine the nuchal translucency, which is commonly known as the “stupidity” of the baby, with an accuracy rate of more than 87%. The third time is from 20 weeks to 24 weeks of pregnancy to screen the fetus from head to toe for abnormalities, such as arm and leg defects, harelip and other morphological abnormalities, which may affect the normal life of the child in the future if fatal abnormalities are found. Prompt termination of pregnancy may be considered. The fourth time is in the 32nd week of pregnancy, the third screening for malformations to “fill in the gaps”. The fifth time is at full term of pregnancy to observe the size of the fetus, fetal appendages such as amniotic fluid, placenta, umbilical cord, etc. Shenzhen has included five necessary ultrasound examinations in the public health insurance program. As early as 2001, the Ministry of Health put forward the plan of “Action to improve the quality of China’s population to reduce birth defects and disabilities”. According to statistics, only 20% of the mothers-to-be in our province do prenatal screening. The authorities in our province are called upon to include the five necessary examinations during pregnancy in the health insurance. Strong support at the policy level could be more effective in reducing the incidence of birth defects in China, thus improving the quality of health of the Chinese population. Some mothers-to-be may also be concerned about the impact of having more ultrasounds on the healthy development of the fetus. According to the study of the Safety Committee of the International Society of Ultrasound in Obstetrics and Gynecology, two-dimensional ultrasound examinations are safe for the fetus, and their ultrasound doses are all within the safe range. Continuous exposure of the fetus for more than 5 minutes should be avoided during early pregnancy. The ultrasound dose of 3-D and 4-D ultrasound is still higher. The Chinese Prenatal Ultrasound Guidelines state that the usefulness of 3D and 4D ultrasound is limited and can be used when necessary. Not all malformations can be seen In 2013, the Chinese Medical Association Ultrasound Physicians Branch “Prenatal Ultrasound Guidelines” pointed out that since the establishment of the early 1970s “perinatal medicine” is a new discipline on the edge of multidisciplinary cooperation. It is characterized by the fact that the fetus is considered an independent life and becomes the object of direct clinical observation. Ultrasound is a new technology that has been promoted only in the 21st century. Through obstetric ultrasound, many fetal anomalies that could not be detected before birth have been detected, contributing to eugenics. However, the study of fetal anatomy, fetal physiology and pathology is still brand new and there are still many unknowns to be researched, so “can be found” does not mean “can definitely be found”. Ultrasound is affected by various factors, including gestational age, fetal position, amniotic fluid, fetal activity, fetal bone shadow, etc. Some organs or parts of the body may not be displayed or may not be visible. This is the limitation of ultrasound examination. The ultrasound result of “no significant abnormality” does not mean “all normal”, the ultrasound examination mainly examines the content of “ultrasound description” in the report, and the fetal structures that are not described are not included in this ultrasound examination. For example, due to the current technical conditions, many human structures such as fetal ear, wrist bone, metacarpal bone, finger bone, talus bone, tarsal bone, metatarsal bone, toe bone, thyroid gland, internal and external genitalia, etc. cannot be examined as prenatal ultrasound examination items, nor can ultrasound show fetal chromosomes, nor can it detect fetal intelligence, vision, hearing, motor function, metabolic diseases, etc. The absence of abnormal fetal structures and morphology already examined does not mean that these structures and functions are not abnormal. Moreover, fetal growth and development is a gradual maturation process, and each ultrasound examination result only represents the level of growth and development at that time. Fetal anomalies are also a dynamic developmental process and cannot be detected by ultrasound examination without reaching a certain stage or degree of development. The scope and role of fetal system screening examinations must be properly understood.