Lung maturation in small for gestational age fetuses from pregnancies complicated by placental insufficiency or maternal hypertension
Introduction
Low fetal weight for gestational age is an important cause of neonatal morbidity and mortality [1], [2], [3]. When fetal weight is below the 10th percentile for gestational age the fetus is designated as being small for gestational age (SGA). SGA may be caused by many factors including placental insufficiency which can be objectified by Doppler ultrasound examination [4]. It has been hypothesized that placental insufficiency may accelerate pulmonary maturation through chronic intrauterine stress [5]. However, to date no studies have been able to confirm this hypothesis [4], [6], [7], [8]. Contrary to expectation, two groups have reported a higher respiratory distress syndrome (RDS) incidence in infants with abnormal prenatal Doppler examination [6], [7]. Furthermore, recently we and others have shown that hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome [9] increases respiratory morbidity in preterm neonates [8], [10], indicating impaired pulmonary development.
If lung development is influenced by placental insufficiency and HELLP syndrome, one would expect to see differences in lung maturation indices in the amniotic fluid. Previous research is inconclusive with the lecithin/sphingomyelin (L/S) ratio being unchanged by maternal hypertensive disease in some studies [11], [12], [13] and decreased in others [14], [15].
To our knowledge, no research has been performed in preterm SGA infants to correlate the L/S ratio and lamellar body count (LBC) with Doppler ultrasound findings and maternal hypertensive disease. We hypothesize that:
- 1)
preterm SGA fetuses with abnormal umbilical artery Doppler ultrasound examination will have a higher L/S ratio and LBC than SGA fetuses of the same gestational age (GA) with normal umbilical artery Doppler ultrasound examination
- 2)
preterm SGA fetuses from mothers with HELLP syndrome will have a similar or lower L/S ratio and LBC compared to SGA fetuses of the same GA with normotensive mothers.
Section snippets
Methods
All neonates born in the Perinatal Center of the University Medical Center, Utrecht, the Netherlands, before 34 weeks of gestation are admitted to the neonatal intensive or high care unit and are prospectively collected in a database. From this database we selected all infants born between 1st January 1997 and 31st December 2003 with birth weight < 10th percentile [16] and GA < 34 weeks. GA was calculated from the last menstrual period and early sonographic examination. For the present study we
Results
In total 76 infants fulfilled the study criteria. Baseline criteria of the study population are shown in Table 1. In 62 cases amniocentesis was performed once, in the remaining cases amniocentesis was repeated. Data from the last amniocentesis before delivery was used in the analyses.
Fig. 1 shows that at each gestational age, the L/S ratio was higher in the abnormal Doppler group than in the normal Doppler group. This difference in L/S ratio was significant before and after correction for
Discussion
The present study showed that the L/S ratio of SGA fetuses is significantly higher in pregnancies with abnormal umbilical artery blood flow velocity waveform patterns (placental insufficiency) and significantly lower in pregnancies complicated by maternal hypertension. Subdivision of the maternal hypertension group showed that low L/S ratios are particularly found in pregnancies complicated by HELLP syndrome. Finally, the LBC did not differ significantly between groups in any of the analyses.
Conflict of interest statement
No financial or personal disclosures.
No funding or study sponsors.
References (26)
- et al.
Morbidity and mortality among very-low-birth-weight neonates with intrauterine growth restriction. The Vermont Oxford Network
Am J Obstet Gynecol
(2000) Syndrome of hemolysis, elevated liver enzymes, and low platelet count: a severe consequence of hypertension in pregnancy
Am J Obstet Gynecol
(1982)- et al.
Fetal lung maturity is not accelerated in preeclamptic pregnancies
Am J Obstet Gynecol
(1993) - et al.
Is lung maturation related to fetal growth in diabetic or hypertensive pregnancies?
Eur J Obstet Gynecol Reprod Biol
(1993) - et al.
The effect of glucocorticoid therapy on fetal lung maturity indices in hypertensive pregnancies
Obstet Gynecol
(1998) - et al.
Lamellar body counts: a consensus on protocol
Obstet Gynecol
(2001) - et al.
Lamellar body counts compared with traditional phospholipid analysis as an assay for evaluating fetal lung maturity
Obstet Gynecol
(2001) - et al.
Lipid hydroperoxides and free radical scavenging enzyme activities in preeclampsia and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome: no evidence for circulating primary products of lipid peroxidation
Am J Obstet Gynecol
(2001) - et al.
Invasive cytotrophoblasts manifest evidence of oxidative stress in preeclampsia
Am J Pathol
(2000) - et al.
Neonatal outcome in small for gestational age infants: do they really better?
J Perinat Med
(1999)