Plasma total calcium levels have been studied in pregnant rabbits and their fetuses from 16 days gestation to term. Between 16 and 21 days gestation the observed fetal plasma calcium level falls from the maternal level or above to 1-6 mg/100 ml. below the maternal level. Thereafter, the fetal plasma calcium rises and at 30 days gestation exceeds the maternal level by 1*9 mg/100 ml. There is a high correlation between fetal and maternal levels at 21 days which is lost by 30 days. Fetal skeletal calcification was studied using an alizarin stain technique. The earliest centres of calcification were present in the clavicle and mandible at 16 days. It is concluded that the observed fall in fetal plasma calcium near mid-gestation may be due to the onset of skeletal calcification and the increase after 21 days to one or more of a variety of factors. Five 21 days pregnant animals were infused with 1 per cent calcium chloride solution (1 g anhydrous calcium chloride in 100 g aqueous solution) for up to 2j hr. The maternal plasma calcium concentration was elevated by 7.7 mg/100 ml. during the infusion but the fetal level was only raised by 2-0 mg/100 ml. The correlation between fetal and maternal levels was lost during the infusion. These findings are compatible with either slow calcium transfer across the placenta or fetal calcium homeostasis. It is well established in many mammalian species that during late gestation there is a greater concentration of calcium in fetal than in maternal plasma. In the guinea pig, on the contrary the fetal plasma calcium concentration at mid-gestation falls from about the maternal level (9.6 mg/100 ml.) to 5-5 mg/100 ml. and then slowly rises, reaching the maternal level again only near the end of gestation [Graham and Scothorne, 1970]. This paper presents a study of maternal and fetal levels, from a relatively early stage in gestation, in another species. The rabbit was chosen since there is already some evidence that fetal levels are lower than maternal at 21-23 days of gestation [McIsaac, 1927; Economou-Mavrou and McCance, 1958]. The stage in gestation when the homeostatic mechanism for calcium becomes mature in the fetus has not yet been identified, although there is experimental evidence that the parathyroid can elaborate hormone early in embryonic development [Scothorne, 1964: Graham and Scothorne, 1971]. In late gestation, when fetal calcium levels are higher than maternal, the fetal level remains constant when the level in the mother is elevated by infusion of calcium chloride [Bawden and Wolkoff, 1967: Greeson et al., 1968]. In this work, when low fetal levels earlier in gestation were substantiated, it was decided to study these levels after induction of maternal hypercalcaemia. METHODS The accuracy of the calcium estimation was assessed by preparing nine separate 5 ml. plasma solutions [Fawcett and Wynn, 1961] each containing 0 05 ml. of the same human plasma. The calcium content of each small sample of plasma was determined 160

Plasma total calcium levels have been studied in pregnant guinea pigs and their foetuses from 26 days of gestation to term. Between 28 days and 33-39 days the foetal plasma calcium falls from nearly the maternal level (9.6 mg/100 ml.) to 5-5 mg/100 ml. Thereafter the foetal plasma calcium rises, reaching the maternal level at term. No trend is found in the maternal levels. Foetal skeletal ossification was studied using an alizarin stain technique. Ossification centres appeared first in the clavicle, face and skull at 26 days of gestation. After 27 days gestation (foetal plasma protein = 1 g/100 ml.) there is a steady rise in foetal plasma protein level and at term foetal and maternal levels are approximately equal. Between 41 days gestation and term foetal blood is consistently more acid than maternal blood and has a higher pCO2 and lower P02. There is no evidence of a progressive change during gestation in pH, P02 or pCO2 in either foetal or maternal blood. It is concluded that the fall in foetal plasma calcium between 28 days and 33-39 days gestation may be due to calcification of the foetal skeleton before the full establishment of calcium homeostasis in the foetus. Increasing foetal plasma protein concentration or foetal parathyroid activity may account for the rise in foetal plasma calcium after 33-39 days.

Parathyroid tissue or pharyngeal pouch tissue containing the presumptive primordium of parathyroid III from embryonic guinea‐pigs has been explanted to the chick chorioallantoic membrane in contact with a piece of neonatal rat parietal bone. Histological study of the conjoined grafts, removed 4–7 days later, showed bone resorption, indicative of parathyroid secretory activity, at developmental ages of 23 days and older.

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Aim To provide an in-depth understanding of the experiences of parents who have had a loss from a multiple pregnancy. Method A qualitative study involving semi -structured interviews. Participants were recruited from a Special Care Baby Unit and a Fetal Medicine department from within the same NHS tertiary hospital. Fourteen parents who had experienced a loss in pregnancy or the neonatal period were interviewed. Data were analysed using a generative thematic approach. Results Parents described feelings of both grief for the loss of their baby and joy at the birth of survivors. This ‘rollercoaster’ of emotions impacted significantly upon parents’ needs whilst in hospital. Firstly, they valued highly the emotional work of those health professionals who acknowledged their bereavement. They also valued continuity of staff care, which allowed parents to build up supportive relationships of trust over time. Secondly, due to the trauma of their loss, coupled with anxiety over the survival of sick siblings, parents felt they had been unable to make fully informed decisions concerning their demised baby. This often left them with feelings of regret. Conclusion Parents who lose a baby from a multiple pregnancy have a specific set of needs which differ from parents who have a singleton loss. As bereaved parents can remain in hospital for many weeks whilst surviving siblings are cared for, the emotional work of health professionals proved crucial to their experiences. The trauma of their bereavement however, was acknowledged by parents as impacting upon their ability to make informed decisions.