Foetal weights

In some reproductive toxicity studies in experimental animals the only effects recorded may be considered of low or minimal toxicological significance and classification may not necessarily be the outcome. These include for example small changes in semen parameters or in the incidence of spontaneous defects in the foetus, small changes in the proportions of common foetal variants such as are observed in skeletal examinations, or in foetal weights, or small differences in postnatal developmental assessments. 

Brunstrom B, Kihlstrom I, Lundkvist U. 1982. Studies of foetal death and foetal weight in guinea pigs fed polycMorinated biphenyls (PCB). Acta Pharmacol Toxicol 50(2) 100-103. 

Foetal growth retardation (FGR) is defined as a predicted foetal weight at term that is under the 10 percentile or below 2.5 kg. It is linked to significantly elevated foetal morbidity and mortality (McCormick, 1985), with the most common causes cited as chronic hypertension, pre-eclampsia, smoking, alcohol, stress and intrauterine infections. It is believed that these conditions cause abnormalities in placental structure and function (Regnault et al., 2002) interfering with implantation, placentation, placental... 

Foetal development promotes growth and differentiation of foetal cells and organogenesis Promotes longitudinal body growth and increased body weight Promotes enhanced functioning of the male and female reproductive tissue Promotes growth and differentiation of neuronal tissue... 

Body weight and food/water consumption Macroscopical examination of all dams for any structural abnormalities or pathological changes, which may have influenced the pregnancy Implantation, resorptions Foetal growth... 

Classification should not automatically be discounted for chemicals that produce developmental toxicity only in association with maternal toxicity, even if a specific maternally-mediated mechanism has been demonstrated. In such a case, classification in Category 2 may be considered more appropriate than Category 1. However, when a chemical is so toxic that maternal death or severe inanition results, or the dams are prostrate and incapable of nursing the pups, it may be reasonable to assume that developmental toxicity is produced solely as a secondary consequence of maternal toxicity and discount the developmental effects. Classification may not necessarily be the outcome in the case of minor developmental changes e.g. small reduction in foetal/pup body weight, retardation of ossification when seen in association with maternal toxicity. 

An increase in body water accounts for a large percentage of weight gain exhibited during a natural pregnancy. This occurs as a result of placental and foetal development, the formation of amniotic fluid and an increased maternal plasma... 

Fig. 175. Non-immunologically stimulated peritoneal macrophages from a SPF-NMRl mouse 48 h after a single intraperitoneal injection of 150 mg isotactic polyacrylic acid (Vi 2329 molecular mass 8-12 kDa cf. Muck et al. 1977) as sodium salt per kg body weight. The produced ascites were centrifuged for 10 min at 1000 r.p.m. and incubated in TCM 199 -I- 20 % foetal calf serum on a plastic cover slip for 2 h, rinsed with phosphate buffered saline after Dulbecco and fixed in 1 % glutaraldehyde in 0.07 M phosphate buffer (pH 7.4). Ethanol, amyl acetate. Critical point drying. Gold coating. Cambridge Stereoscan 150 operated at 19 kV. APh-R. 101/80, negative 03 773. (from Schiller 1982)...

Table 1. The energy metabolism measured as metabolizable energy (ME), heat production (HE), retained energy (RE), retained fat (RF) and body weight as well as the oxidation of protein (OXP),fat (OXF), and carbohydrates (OXCHO) in male mink kits exposed to adequate (FAPl) or low (FLPl) protein levels during foetal life combined with adequate (AP) or low (LP) protein allowance from 7 to 9.5 weeks of age.

---