Semen samples from 31 men, all of whom had fathered a child within the preceding year, were analysed for sperm characteristics and for the content of prostaglandins (PGs). Mean concentrations (mg/l) for the four main groups of PGs were 67.1 for PGE, 3.2 for PGF, 245.7 for 19-hydroxy-PGE and 13.3 for 19-hydroxy-PGF. The individual values were distributed over a relatively wide range but the extremely wide ranges reported by previous authors were not confirmed. Information is also presented concerning the relative proportions of the four isomers of PGF, as well as those of 19-hydroxy-PGF. Only sperm density was related to PG concentration in fertile men. Polyzoospermia was associated with a low PGE concentration.

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The semen quality of men who participated in an infertility investigation in 1956 was compared with that from men from similar populations in the years 1966, 1976, and 1986. The sperm parameters studied included total sperm count and sperm morphology. A significant reduction over this 30-year period was observed for both parameters. The total sperm count decreased from 467 million in 1956 to 305 million in 1986 (mean, p < 0.OOOl) and the percentage of sperm with normal morphology diminished from 53% to 37% (mean, p < 0.0001) during the same period. This Swedish study, like studies in other industrialized countries, indicates a decline in semen quality over the past few decades.

Feeding routines in the maternity ward were investigated in 204 mother-infant pairs before and in 203 after a change towards earlier, more frequent breastfeeding and elimination of routine substitute feeds. In the intervention group, the volume of breast-milk increased, while the use of formula and sugar solution decreased correspondingly. The infants in the intervention group lost more weight during the first 2-3 days (6.4% versus 4.6%), but regained their birth weight faster than the supplemented control group. The incidence of hyperbilirubinemia was not significantly different in the two groups. No cases of hypoglycemia were diagnosed. At 6 months, 87% of the infants in the intervention group were still fed at the breast, compared with 66% in the control group. The weight curves were comparable up to 9 months, when intervention group infants were found to weigh slightly less. These follow-up results must be interpreted with some caution due to the low but comparable response rate of the two groups. Thus the intervention study demonstrated that healthy, full-term infants usually have no need for supplements to their mothers' milk provided they have had a satisfactory start in life with early and frequent feeds at the breast. The follow-up study indicated that a more "physiological" start of breastfeeding may have had a positive long term effect on the overall duration of the lactational period.

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