MATERNAL SERUM ZINC, CORD BLOOD ZINC AND BIRTH WEIGHT OF TERM NEWBORN INFANTS IN JOS, PLATEAU STATE, NIGERIA

Abstract

Adequate supply of zinc is essential for optimal fetal growth because of the
role of zinc in cellular division, growth and differentiation. Low maternal
serum zinc has been associated with low birth weight, which in turn is
associated with increased morbidity and mortality in newborn infants.

In Nigeria, where the prevalence rates of zinc deficiency among pregnant
women, low birth weight and infant mortality are high; it will be useful to
determine the relationship between maternal and cord serum zinc levels and
birth weight.

This was a cross sectional study carried out at the antenatal clinic and labour
ward of the Jos University Teaching Hospital, Jos, Nigeria to determine the
association between maternal serum zinc, cord serum zinc and birth weight of
term newborn infants.

One hundred and ninety mothers and their singleton, term babies were
recruited. Babies’ weights were measured within thirty minutes post-delivery.
Blood samples were collected from the mothers and cord of the babies
immediately after delivery for serum zinc analysis using atomic absorption
spectrophotometry.
The mean age of the mothers was 28.29 ± 5.64 years (range 17- 43 years) and
the mean gestational age of the babies was 39.2 ± 1.2 weeks (range 37 –42
completed weeks).

The mean birth weight of the babies was 3106.7 ± 411.2 g (range 1900
4100g) and the prevalence of low birth weight (<2500g) was 6.3%.
The mean maternal serum zinc concentration was 48.5 ± 17.6 µg/dl (range
12- 101 µg/dl) and the prevalence of maternal zinc deficiency (serum zinc
concentration < 50 µg/dl) was 52.1%.
The mean cord serum zinc concentration was 99.3 ± 21.5 µg/dl (range 45-
158µg/dl). Majority (96.8%) of the babies had normal cord serum zinc
concentration (>65 µg/dl). Males had higher mean cord serum zinc (99.9 ±
22.2 µg/dl) than females (98.7 ± 20.9 µg/dl) but this was not statistically
significant (p = 0.70).

There was no statistically significant association between the maternal and
cord serum zinc (p = 0.62); neither was there a significant association
between the maternal serum zinc and birth weight (p =0.99). However, there
was statistically significant positive association and correlation between cord
serum zinc and birth weight (p < 0.001, r = 0.02, p= 0.04).

The outcome of the study indicates that in spite of low maternal serum zinc
level, adequate amount of zinc could be transferred to the babies thereby
preventing zinc deficiency in the babies and aiding their growth. Also, cord
serum zinc level is a determinant of birth weight and could be a better
indicator for the assessment of fetal growth than maternal serum zinc level.
On the account of the above findings, more studies need to be done to
determine the full mechanism of fetal accretion of zinc in pregnancy.

MATERNAL SERUM ZINC, CORD BLOOD ZINC AND BIRTH WEIGHT OF TERM NEWBORN INFANTS IN JOS, PLATEAU STATE, NIGERIA