Prior treatment for Depression

The probability that a UK woman is treated for depression at some time in her life is reported variously as between 17% and 25%. Comparable data for the US suggest a rate of '1 in 5'.

By comparison, 33% of our sample reported previous treatment for depression. This is a certainly a larger fraction, but whether or not it is significantly so, depends on the confidence that is attributed to the global estimates. It seems likely that earlier depressive episodes are associated with PND, but the evidence here is not conclusive.

Examination of the possibility that prior depressive episodes might be associated with subsequent (post PND) episodes or with likelihood that PND is invariably associated with pregnancy were even less conclusive. More data may make things clearer.

Frequency of (subsequent) PND Experiences

Interpretation of these results is not as straightforward as it may seem.

When this questionnaire was devised it was not appreciated that birth rates had got as low as they have. On the basis of the rates for year 2000, the average number of children born to a UK mother is expected to be 1.7.

On the basis of that statistic, the number of mother who have three or more children — and could possibly respond positively to "Yes, but not for every birth" — is likely to be very small. Similarly many, if not most, of the women responding positively to "an episode of PND has accompanied each birth" are referring to a single subsequent pregnancy.

The figures aren't quite as meaningless as this might suggest because the average number of children born to a mother who already has one child is not 1.7 but 2.2. Furthermore since they are more likely to relate to the birth rates prevailing in 1980 than those of 2000, the figure of the completed family size is more likely to average 2.5. Nevertheless the distinction between "Yes, but not for every birth" and "an episode of PND has accompanied each birth" is probably irrelevant.

The fact that 52% of the sample have no further children might indicate that a single experience of PND is sufficient a disincentive to shelve plans for any more babies. To test this conjecture we need some estimate of the proportion of all just-delivered mothers who decide to call it a day and have no further children.

Using data from the UK's Population Trends 108 of Summer 2002, and basing calculations on birth rate data for 1980 the figure of 44% was calculated. It is not an obvious calculation, so it might well be wrong, but if correct it suggests that PND represents an effective contraceptive.