 | ||
|
| |    The 'Crown-Rump' Measurement How ultrasound helps to determine fetal age by Laura Jana, M.D., F.A.A.P. reviewed and revised by Marjorie Greenfield, M.D. While some parents can identify the day they conceived, others are less sure. And while obtaining an accurate estimate of the fetus' age is often quite useful to the parents (so that they can start preparing for their new arrival), it can be doubly helpful for the practitioner. That's because many prenatal care recommendations and test interpretations are based on fetal age. One way to determine that age is through the use of ultrasound. When you go in for a fetal ultrasound, you're likely to notice that the person doing the test is taking several measurements of your baby on the ultrasound screen. One of these measurements is taken from the top of the baby's head, or crown, to his bottom, or rump. This measurement is considered to be the most accurate method for determining fetal age early in pregnancy and can be obtained as early as six weeks. This accuracy is possible because fetuses follow a very predictable growth rate in the first trimester. However, later in pregnancy, a baby's size can vary considerably due to a combination of factors, making measurements (such as the crown-rump length) much less useful in determining fetal age. A typical nine-week-old fetus has a crown-rump measurement of a bit over two centimeters (about the length of a large bee) and has a head that is quite big relative to the rest of his body. When your baby's crown-rump measurement is compared to a set of standard lengths, the result is an estimated age that is considered to be accurate within five days.
| |  | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| About Us |
Contact Us |
Our Partners Privacy Policy | Ethics | Advertising Policy | Terms of Service © Copyright 2004 The Dr. Spock Company. All Rights Reserved. THIS SITE DOES NOT PROVIDE MEDICAL ADVICE. The information drSpock.com
provides is for educational purposes only and is not a substitute for
professional medical advice. Always seek the advice of your health care
professional if you have a specific health concern. Mention or advertisement
of any product, service, or brand does not constitute endorsement, guarantee,
or recommendation by The Dr. Spock Company. Please read our full
Terms of Service. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
