<P> The embryo and fetus float in the amniotic fluid inside the uterus of the mother usually in a curved posture resembling the letter C. The measurement can actually vary slightly if the fetus is temporarily stretching ( straightening ) its body . The measurement needs to be in the natural state with an unstretched body which is actually C shaped . The measurement of CRL is useful in determining the gestational age ( menstrual age starting from the first day of the last menstrual period ) and thus the expected date of delivery ( EDD ) . Different babies do grow at different rates and thus the gestational age is an approximation . Recent evidence has indicated that CRL growth ( and thus the approximation of gestational age ) may be influenced by maternal factors such as age , smoking , and folic acid intake . Early in pregnancy it is accurate within + / - 4 days but later in pregnancy due to different growth rates , the accuracy is less . In that situation , other parameters can be used in addition to CRL . The length of the umbilical cord is approximately equal to the CRL throughout pregnancy . </P>
<P> The embryo and fetus float in the amniotic fluid inside the uterus of the mother usually in a curved posture resembling the letter C. The measurement can actually vary slightly if the fetus is temporarily stretching ( straightening ) its body . The measurement needs to be in the natural state with an unstretched body which is actually C shaped . The measurement of CRL is useful in determining the gestational age ( menstrual age starting from the first day of the last menstrual period ) and thus the expected date of delivery ( EDD ) . Different babies do grow at different rates and thus the gestational age is an approximation . Recent evidence has indicated that CRL growth ( and thus the approximation of gestational age ) may be influenced by maternal factors such as age , smoking , and folic acid intake . Early in pregnancy it is accurate within + / - 4 days but later in pregnancy due to different growth rates , the accuracy is less . In that situation , other parameters can be used in addition to CRL . The length of the umbilical cord is approximately equal to the CRL throughout pregnancy . </P>
when do they stop measuring crown to rump
when do they stop measuring crown to rump
later in pregnancy
later in pregnancy