Birthweight by gestational age and sex at a rural referral center.

OBJECTIVE

Determine the distribution of birthweights in singleton births by gestational age and gender at Marquette General Hospital, a rural referral center in Michigan's upper peninsula.

STUDY DESIGN

Birth log data were examined for prenatal factors and obstetrical outcomes. The birthweight distribution was compared to published values, and a linear regression model of prenatal factors was developed.

RESULTS

Our median birthweights were significantly greater than published values. Males were 128 g heavier than female infants after adjusting for gestational age. In a multivariable linear regression model, birthweight was significantly associated with gestational age, sex of the infant, maternal age, primigravida status of mother, and maternal diabetes (all p<0.01). Using published standards resulted in an overdiagnosis of large for gestational age and an underdiagnosis of small for gestational age.

CONCLUSION

Local birthweight distributions can differ significantly from historical or national distributions. The development of birthweight distributions accommodating for prenatal factors is needed.