Crown Rump Length As A predictor Of Fetal Weight At Birth

Abstract

Accurate assessment of fetal weight is an integral part of obstetric practice. It provides information for planning the mode of delivery and management of labor. It is well known that both low birth weight (BW) and excessive fetal weight are associated with an increased risk of newborn complications during labor and the first post-natal period (Prechapanich et al., 2004). The birth weight is an important factor in the outcome of a pregnancy. It is well known that prenatal morbidity and mortality increase in abnormal birth weight range fetuses. They also have poor developmental outcomes. In addition, marked birth traumas have been increased in macrosomic infants. The accurate antenatal measurement of fetal weight is very important. It gives useful information for fetal growth assessment, information that could help to decide the time of delivery, the need for specific obstetrical intervention and delivery at an equipped center. (Schild et al., 2007). The aim of the present study is to assess the value of using ultrasound measurement of first trimester crown rump length (CRL) as a predictor of birth weight. This prospective observational cohort study was conducted at Ain Shams University Maternity Hospital from September 2012 till December 2013 at Ain Shams Maternity Hospital and included 90 uncomplicated pregnant women who attended the outpatient clinic at Ain Shams University Maternity Hospital; Ultrasound examination was done at the fetal care unit with ultrasound Machine Medison SONOACE R5 with multi frequency abdominal probe 4-7 MHZ at gestational age 12.0 to 12.6 weeks taking in consideration that the patient had accurate gestational dating for a singleton viable pregnancy and excluding multiple pregnancy, Pregnancies without accurate dating, the patient suffering from any obstetrical or medical problems gestational or pre gestational, the patient delivered preterm, polyhydramnios, the patients became hypertensive or developed gestational diabetes or other medical conditions occurred during pregnancy, known genetic or congenital malformation & patients with BMI less than 18.5 or more than 25 kg/m2 . Each pregnant patient underwent ultrasound assessment of first trimester crown rump length at 12.0 to 12.6 weeks Then follow up of the patient and Second & third trimester ultrasound assessment of fetal anatomy and fetal biometry including Bi-parietal diameter (BPD) , femur length (FL) and abdominal circumference (AC), the estimated fetal weight (EFW) was calculated by formula of Hadlock 2 (based on BPD, FL and AC) ( Log,oB W = 1.335- (0.0034X AC X FL) + (0.0316 BPD)+(0.04s7)( AC) +(0.1623X FL). (Hadlock et al., 1985) The newborns was weighted after delivery using a graduated scale and the actual birth weights (ABWs) was recorded, either average for gestational age or not and classify the fetuses into:- Appropriate for gestational age with average birth weight, large for gestational age with weight above the 90th percentile at gestational age or small for gestational age with weight below the 10th percentile at gestational age. The study showed that sonographic assessment of first trimester crown rump length can be used as predictors of small for gestational age (SGA), average for gestational age (AGA) and large for gestational age (LGA) (table (15), page 115). And The correlation between first trimester CRL and 2nd trimester EFW was a statistically significant positive correlation (r = 0.438, P <0.001) and the correlation between frist trimester CRL and 3nd trimester EFW was a statistically significant positive correlation (r = 0.358, P <0.001). We found that the correlation between first trimester CRL and actual birth weight at delivery was a statistically significant positive correlation (r = 0.413, P <0.001).