Meconium-stained amniotic fluid across gestation and neonatal acid-base status.
OBJECTIVE
To estimate whether the acid-base status of neonates born to women with meconium-stained amniotic fluid varies across gestation.


METHODS
We carried out a retrospective cohort study of all pregnancies that were complicated by meconium-stained amniotic fluid in 2004. Cases were identified from a perinatal pathology database that contained data on all pregnancies complicated by meconium-stained amniotic fluid. Data abstracted from the charts included gestational age at delivery, umbilical arterial pH, birth weight, and the presence or absence of labor. Cases were stratified according to gestational age at delivery. The distribution of meconium-stained amniotic fluid across gestation was computed. The mean umbilical arterial pH values (with 95% confidence intervals) across gestation were assessed by analysis of variance.


RESULTS
The mean umbilical arterial pH in women with meconium-stained amniotic fluid did not differ across gestation. The overall incidence of meconium-stained amniotic fluid was 12.0% (766 of 6,403 deliveries). The rates of meconium-stained amniotic fluid increased from 1.2% at 32 weeks to 100% at 42 weeks.


CONCLUSIONS
The rising incidence of meconium-stained amniotic fluid with gestational age is consistent with the hypothesis that fetal maturation is a major etiologic factor in meconium passage. Also, the lack of variation of mean umbilical arterial pH across gestation suggests that fetal acidemia is not increased when meconium passage occurs earlier in pregnancy rather than at later gestational ages.
Oyelese
Yinka
Y
Department of Obstetrics, Gynecology, and Reproductive Sciences, Division of Maternal-Fetal Medicine, UMDNJ, Robert Wood Johnson Medical School/Robert Wood Johnson University Hospital, New Brunswick, New Jersey 08901-1977, USA. YinkaMD@aol.com
Culin
Angelina
A
Ananth
Cande V
CV
Kaminsky
Lillian M
LM
Vintzileos
Anthony
A
Smulian
John C
JC
D000328:Adult; D000653:Amniotic Fluid; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015994:Incidence; D007231:Infant, Newborn; D008470:Meconium; D009515:New Jersey / Q000453:epidemiology; D007744:Obstetric Labor Complications / Q000453:epidemiology* / Q000209:etiology; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D014469:Umbilical Arteries