MATERIALS AND METHODS

Fifty four pregnant women at delivery and their corresponding full term (gestational age ranging between 37 and 42 weeks) newborns were selected from Al-Mataria Teaching Hospital during the year 2004-2006 constituted the material of this study. They were chosen to be free of hypertension, diabetes and toxemia of pregnancy, ante-partum hemorrhage or any medical or obstetric problems that may interfere with intrauterine growth and development. They had normal vaginal delivery. Anthropometric measurements of the mother including weight, height and BMI were recorded. Measurements of the newborn including weight, length, head circumference, arm circumference, chest circumference and Ponderal Index (PI = weight in grams/length in cm³) were recorded too. Cases were put into two groups: low birth weight equal to or less than 2.5 kg (n = 24) and control above 2.5 kg (n = 30).

Venous blood samples, 5 mL each, were collected from each woman before delivery and similar amounts of mixed arterio-venous cord blood were collected from each corresponding newborn infants at birth. Serum was separated and stored at -20°C until further assayed. Serum albumin was determined using spectrophotometric technique (Doumas et al., 1971). Serum prealbumin, retinol binding protein, transferrin and fibronectin were determined using radial immunodiffusion kit (Mancini et al., 1965).

Statistical analysis using the SPSS program of personal computer version 10 employed the student’s t-test for comparison of the mean values and the simple correlations. Pearson Correlations were calculated to evaluate the relationship between the variables. p-values were two-tailed and values <0.05 were considered statistically significant.

RESULTS

Maternal mean weight, height and BMI were 54.33±11.73 kg, 153.50±5.40 cm and 22.99±4.50 kg m^-2, respectively in low birth weight infants group. The mothers of control group had means of 67.25±16.45 kg, 162.79±8.92 cm and 25.65±5.31 kg m^-2, respectively. Weight and height differences were statistically significant. The low birth weight infants group had a mean newborn weight of 2200±117.95 g, mean length of 48.50±0.78 cm, mean PI of 1.930±0.147 g cm^-3, mean head circumference of 32.33±1.63 cm, mean chest circumference of 31.67±1.74 cm and mean arm circumference of 10±1.32 cm. The mean values of the control group were 3295.83±371.56 g, 50.33±2.28 cm, 2.599±0.357 g cm^-3, 33.25±1.39, 33.23±1.12 and 11.13±0.95 cm, respectively. Differences in neonate weight, length, PI, head circumference, chest circumference and arm circumference were statistically significant (Table 1).

In low birth weight infants group, the mean values of maternal serum prealbumin, albumin, retinol binding protein, transferrin and fibronectin were 18.400±4.169, 3.417±0.447, 2.750±1.478, 4.717±0.937 and 9.5167±11.029 mg dL^-1, respectively. These figures were 18.763±5.580, 3.737±0.422, 2.833±1.050, 4.571±1.985 and 19.892±11.311 mg dL^-1, respectively in the control group. Only the maternal albumin and fibronectin in low birth weight group were significantly lower than in the control group. The mean values of the tested nutritional biochemical parameters in cord blood of low birth weight neonates' were 14.883±2.389 mg dL^-1, 3.867±0.281 g dL^-1, 1.65±1.04 mg dL^-1, 2.317±0.314 g L^-1 and 1.800±1.463 mg dL^-1, respectively, while values in the cord blood of control group were 14.425±4.585 mg dL^-1, 4.075±0.415 g dL^-1, 1.55±0.87 mg dL^-1, 2.275±1.325 g L^-1 and 6.888±5.055 mg dL^-1. Only cord blood fibronectin was significantly lower in low birth weight neonates than in control group (Table 2).

In low birth weight group, the maternal weight was positively correlated with each of the neonatal weight, PI and cord blood fibronectin and negatively correlated with each of neonatal length, head and chest and arm circumferences.

Table 1:	The maternal and the neonatal anthropometric measurements
NS = Not Significant

Table 2:	Maternal and Cord biochemical parameters
NS = Not Significant

Table 3:	Correlation between significant maternal and neonatal variables in the low birth weight group
**: Correlation is significant at the 0.01 level (2-tailed), *: Correlation is significant at the 0.05 level (2-tailed)

Table 4:	Correlation between significant maternal and neonatal variables in the control group
*: Correlation is significant at the 0.05 level (2-tailed)

BMI positively correlated with each of the neonatal weight and cord blood albumin and fibronectin. It was negatively correlated with each of the neonatal length, PI, head and chest and arm circumferences. The maternal albumin positively correlated with each of the neonatal length, head and chest and arm circumferences. The maternal fibronectin positively correlated with each of the neonatal length, PI and cord blood fibronectin. It was negatively correlated with each of the neonatal head and chest and arm circumferences (Table 3).

The maternal height positively correlated with the neonatal weight of both the low birth weight group and the control group (Table 3, 4).

DISCUSSION

Literature confirms the traditional state that anthropometric measurements of pregnant mothers assess their nutritional status (Bissenden et al., 1981). The BMI is an age dependent index for nutritional status evaluation (Guthrie, 1989). Recent studies showed that intrauterine malnutrition have more serious consequences for children than postnatal malnutrition. Low pre-pregnancy BMI is considered a risk factor for preterm birth and intra-uterine growth retardation (Kruger, 2005). Hulsey et al. (2005) reported that appropriate maternal BMI at conception followed by adequate weight gain during pregnancy may have a substantial influence on reducing the number of low birth weight deliveries. Women with less than adequate weight gain were 1.4 times more liable to deliver a very low birth weight baby and 1.9 times more likely to deliver moderately low birth weight baby as compared with women with adequate weight gain. Kulkarni et al. (2006) reported that maternal lean body mass was found to be the most important determinant of birth weight. Thame et al. (2004) found that maternal weight and weight gain was directly related to fetal anthropometry through influencing the placental volume and the rate of placental growth. Neonatal nutritional status is measurable using weight and length versus gestational age (Graitcer et al., 1981). The PI is used to calculate the relative amount of soft tissue present in an infant (Miller and Hassanein, 1971). Hendricks (1990) stated that PI is the accurate indicator of body built and nutritional status. The neonate mid-arm and chest circumference measures are simple, quick, easy and cheap indicator for birth weight. Arm circumference reflects skeletal muscle protein and fat stores (Raubenstine et al., 1990). A mid-arm circumference usually measures less than 9.0 cm when birth weight is less than 2500 g. Neonatal mortality was shown to have an inverse relation with mid-arm circumference (Ahmed et al., 2000). Naik et al. (2003) reported that chest circumference had the maximum sensitivity of detecting low birth weight in newborns. While the current study proves a positive correlation between mother weight and BMI on one side and newborn weight and PI on the other, the correlation between mother weight and BMI on one side and neonatal mid-arm and chest circumference on the other side was negative.

Literature shows contradictory relations between birth weight and maternal prealbumin, transferrin and retinol binding protein. While some workers (Bhatia and Ziegler, 1983; Xu Shi-Xia, 1993; Jain et al., 1995) proved these relations, the current work, similar to others (Raubenstine et al., 1990; Wong and Saha, 1991; Maher et al., 1993; Maier et al., 1999; Wu et al., 2004b), has not. Physiologic changes associated with pregnancy including plasma volume expansion and pregnancy related effects on protein biosynthesis in the liver were theoretically attributed as factors behind negative relations. Dissanayake and Desilva (1984) could detect a significant correlation between birth weight and cord blood transferrin in the very low birth weight infants only. The risk of being born with 2500 g and below did not appear to depend on the newborn albumin level. This current results match (Raubenstine et al., 1990; Vudhiviai et al., 1990) with two papers and contradict other two (Lao et al., 1990; Hasin et al., 1996). The maternal and cord blood fibronectin was found not correlated with the birth weight. Literature shows similar (Valletta et al., 1988) and contradictory (Taylor et al., 1991; Tamas et al., 1992; Wang et al., 2001) results. Maternal hypo-albuminemia was found to have negative impaction on the anthropometric measurements of the newborn. Bar-Or et al. (2005) reported elevated maternal plasma levels of cysteinylated albumin and decrease in levels of total albumin in intrauterine growth restriction pregnancies.

CONCLUSION

Mother underweight and low BMI reduce newborn weight. Hypo-albuminemia has a negative impaction on newborn length and head, chest and arm circumferences. Low fibronectin reduces newborn body length and PI while low prealbumin, retinol binding protein and transferrin have no influence on fetal growth.