Gestational age

The incidence and severity of ROP both rise with decreasing birthweight and gestational age. Fielder et al. (1992) have shown that the incidence of ROP in infents of < 1700 g birthweight is about 50%, although only 5% had severe disease. Severe ROP results in vitreous haemorrhage from new vessel formation on the immature retina, retinal traction and eventually retinal detachment (Fig. 9.6). In the most severe cases, retinal detachment is complete, resulting in total blindness. Treatment with cryotherapy or laser has halved the incidence of retinal detachment. 

Lubchenco, L.O. Hansman, C. and Boyd. E. Intrauterine growth in length and head circumference as estimated from live births at gestational ages from 26 to 42 weeks. Pedi at.ri cs 37 404-408, 1966. 

Positive urine human chorionic gonadotropin followed by positive ultrasound, fetal heart sounds, and/or fetal movement. Pregnancy Dating and Gestational Age Calculated from the first day of the last menstrual period. 

Age-related variations in central nervous system (CNS) neurotransmitter production and receptor sensitivity are the most likely explanations for the pharmacodynamic differences observed between children and adults following administration of psychotropic medications [39a], Children have lower phenobarbital ratios than adults, and the ratio increases with gestational age [40,41]. Conversely, a lower therapeutic range for children has been identified for cyclosporine, phenytoin, and digoxin [42]. 

Prenatal (general population) Developmental Reduced birth weight and/or reduced gestational age, and/or increased incidence of stillbirth and neonatal death 12-17 Bornschein et al. 1989 McMichael et al. 1986 Moore et al. 1982 Ward et al. 1987 Wibberley et al. 1977... 

NS (general population) Developmental No association between blood lead levels and birth weight, gestational age, or other neonatal size measures 3-55 Factor-Litvak et al. 1991 Greene and Ernhart 1991... 

A cross-sectional study of 236 mothers and their infants in Glasgow, Scotland, demonstrated reductions in gestational age with increasing cord or maternal PbB lead levels (Moore et al. 1982). In the 11 cases... 

The effects of low levels of lead on birth weight and gestational age are controversial. The earlier evidence for such effects was not reproduced in more studies by Factor-Litvak et al. (1991) and Greene and Emhart (1991). A significant inverse association between prenatal maternal blood lead levels and birth weight was reported in the Cincinnati study (Bomschein et al. 1989 Dietrich et al. 1986, 1987a). 

Longnecker, M. P., Klebanoff, M. A., Zhou, H. and Brock, J. W. (2001). Association between maternal serum concentration of the DDT metabolite DDE and preterm and small-for-gestational-age babies at birth . Lancet, 358(9276), 110-114. 

It needs to be mentioned here that there remains some controversy over the placental expression of P-gp as a function of gestational age. An immunohis-tochemical study done by Macfarland et al. showed that P-gp was localized to the microvillous border of trophoblasts in first trimester placenta, but not in term placenta [85], Subsequent studies refuted this to show that MDR1 mRNA is present throughout pregnancy [94], More recently, enzyme-linked immunosorbent assay (ELISA) performed in syncytial microvillous membrane showed that P-gp protein expression in early gestational age placenta is about... 

H.E. Meyer Zu Schwabedissen, M. Grube, B. Heydrich, K. Linnemann, C. Fusch, H.K. Kroemer, and G. Jedlitschky. Expression, localization, and function of MRP5 (ABCC5), a transporter for cyclic nucleotides, in human placenta and cultured human trophoblasts Effects of gestational age and cellular differentiation. Am J Pathol. 166 39 18 (2005). 

Neonatal Cocaine freely crosses the placental barrier, and prenatal exposure to cocaine alters neurobehavioral development in rat pups (Sobrian et al. 1990). The effects on humans exposed prenatally to cocaine is a complicated matter, because so many other concurrent factors contribute to development. Common confounds are prenatal care and maternal polydrug use. Prenatal cocaine use is associated with reduced gestational age, birth weight, body length, and head circumference (Richardson et al. 1999). In children exposed prenatally to cocaine, some studies have shown behavioral differences evident at 1 to 3 years of age (Richardson et al. 1993 Richardson 1998). Associations are also made with impulsivity and attention deficits at age 6 (Leech et al. 1999). 

Cannabinoids are teratogenic and should be avoided during pregnancy. Cannabis use during pregnancy is associated with lower gestational age... 

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