Guidelines for thromboprophylaxis in pregnancy are usually based upon clinical observations and expert opinion. For optimal impact, their use must be attended by consistency in the advice given to women. In this observational study, we evaluated the performance of a scoring system, used as a guide for clinicians administering dalteparin to pregnant women at increased risk of venous thromboembolism. The work included 47 women treated with dalteparin prior to adoption of the scoring system and 58 women treated with dalteparin after its adoption. The indication for thromboprophylaxis was recorded in each case together with details of the regimen employed, obstetric, and haematological outcomes. The main outcome measure was to determine whether consistency improved after adoption of the scoring system. We also recorded the occurrence of any new venous thromboembolism, haemorrhage, the use of regional anaesthesia during labour, evidence of allergy, and thrombocytopenia. We found that use of the scoring system improved the consistency of advice and increased the mean duration of thromboprophylaxis. None of the subjects suffered venous thromboembolism after assessment using the scoring system. There was no increase in obstetric or anaesthetic morbidity when dalteparin was given antenatally period and no evidence of heparin-induced thrombocytopenia.

Summary. Four groups of normal rats have been studied to elucidate the effect on the time of birth of four different light regimes applied throughout pregnancy (day 1 : beginning of pregnancy). The results showed that the time of parturition (onset of expulsion) depended on the light treatment : the longer the duration of the daily illumination, the longer pregnancy lasted. With a 14 hrs light regime, the births occurred during two main periods : 50 p. 100 before 8 p.m. on (Signoret, 1969) rats (Naaktgeboren and Slijper, 1970) and humans (Kaiser and Halberg,1962). In the rat, a specific effect of light on the time of parturition has been suggested in experiments involving shifts of the light/dark cycle (Lincoln and Porter, 1976) or different lengths of daily illumination (Plaut et al., 1970 ;Mitchell and Yochim, 1970 (Boer et al., 1975 ;Cohen, 1976).Attempts to establish if the pineal gland was involved in this effect of light in the rat have been unsuccessful Lincoln and Doyle, 1978) (Krieger, 1974 ;Ixart et al.,1977). Parturition was found to occur invariably during the period when the corticosterone levels were minimal for two different photoperiodic treatments (Lincoln and Porter, 1979). Some studies have also suggested that these adrenal secretions play a role in the initiation of parturition (Yoshinaga, 1978), even if there are controversial interpretations as to the action of the fetal hypophyseal-adrenal axis on the duration of pregnancy in this species (Swaab et al., 1977). Metopirone which inhibits 11! and 18 steroid hydroxylase activity, passes through the placenta (Dupouy, 1972) and leads to a prolongation of gestation (Parvez et al., 1972 (Fuchs, 1969) since the duration of expulsion varies and seems independent of the day of parturition (Boer et al.,1975 figure 3. Under the control light regime (14L-10D) parturition occurred earlier in the adrenalectomized rats (group CA-) than in the corresponding rats (group C ; P < 0.05). Thus, 17.4 (Plaut et ai., 1970 ;Boer et al., 1975 ;Cohen, 1976 ;Lincoln and Porter, 1976)

Summary. In order to study the respective effects of photoperiod and feeding rhythm on the time of birth in rats, the onset Introduction.

Summary. We report two experiments studying the effect of stress on the course of labor and on the time of parturition in the parturient rat. In the first experiment, different stresses were applied after expulsion of the first fetus. A simple manipulation of the female or a change of territory did not modify the whole expulsion phase but increased variability in the birth of the second fetus. By comparison, a strong stress lengthened the duration of expulsion and influenced the time intervals between the first births. A comparison of these results with those obtained after adrenalectomy indicated that the inhibitory effect of a strong stress was probably due to maternal adrenal epinephrin secretion. In the second experiment, a stress was applied before labor in normal rats submitted to two light regimes. In these conditions, the treatment essentially stimulated the last parturitions, which occurred earlier than in control animals.The course of labor and the time of fetal expulsion are known to be influenced by an environmental change or by any event felt as stress. The bitch, for example, often has a labor affected by a disturbance of its usual life conditions (Bleicher, 1962 ;Freak, 1962). In domestic animals such as the pig (Signoret, 1969) Figure 4, which includes the 5 groups of normal rats, shows that this perinatal mortality is related to duration of the labor expulsion phase.After adrenalectomy, with or without a stress after expulsion of the first fetus (lots A-and A-+ S), the total lenght of the expulsion phase did not differ from that of the normal rats (lot N) (P > 0.05). But figure 5 shows that the mean increase of expulsion time at each additional birth was slightly higher in the adrenalectomized rats than in the normal ones. This was partially due to the greater variability of the first two intervals between the first three births ( fig. 5) in lots A-and A-+ S. As the number of animals was too small in these lots, interval distributions have not been compared to the control. On the other hand, figure 5 shows the close evolution of the mean increase of expulsion time at each additional birth in normal rats submitted to a strong stress (lot 5) fig. 3).These results demonstrate that a stress at this stage of pregnancy has not only an inhibitory effect on the course of labor, as has often been emphasized (Newton et al., 1968 ; Naaktgeboren and Bontekoe, 1976), they also show this effect can be attributed to epinephrin secretion since 5 !.g of this catecholamine produced the strong stress response of normal rats in adrenalectomized ones (fig. 5). These data agree with observations obtained on the uterine activity of parturient rabbit or sheep (Naaktgeboren and Bontekoe, 1976). But epinephrin causes three types of response in the myometrium and it has been stated that they depend on the hormonal status of the animal. Abe (1970) gives evidence that the rat uterus has both alpha and beta receptors and that their number in that organ may be steroid-dependent (Williams and Lefkowitz, 1977 ;Roberts et...