According to the urban-legends analysis experts Snopes:

It is a common belief that the number of conceptions increases during natural disasters or crises that keep people confined within their homes for unexpectedly long periods of times. Nine months after such events — blackouts, blizzards, earthquakes, erupting volcanoes, ice storms, and even strikes by professional football players — reports about "baby booms" in local hospitals invariably appear in the media. However, these "booms" always turn out to be nothing more than natural fluctuations in the birth rate (or, in many cases, no variation in the birth rate at all).

In particular, the story, widely believed and cited as fact, that there was a ‘baby boom’ nine months after the great blackout of 1965, is false:

Despite initial reports of New York City hospitals' seeing a dramatic increase in the number of births nine months after the 1965 blackout, later analyses showed the birth rate during that period to be well within the norm.

A series of three articles appearing in The New York Times from August 10-12 in 1966 reported larger-than-average numbers of births at several area hospitals, leading many to declare that the ten-hour overnight blackout the city experienced nine months earlier had led to an unusually high number of conceptions that evening. As often happens, however, people formed predetermined conclusions and then tried to fit the data to them. The birth rate nine months after the blackout did not show a statistically significant difference from the rate of birth recorded during the same period in any of the five previous years.

Earlier today a BBC journalist (if we were adopting the BBC's standards, we should say ‘journalist’), Nick Bryant, stated in a BBC News 24 report from New York:

The only talk of boom here is the baby variety. During the last blackout in the 1970s, there was a spike in the birth rate.

Should we believe him? Did he check the story with hospital records? Did he make it up? Did he confuse the 1977 blackout with the 1965 one and fail to check whether it was true?

Is it really true that no one in New York is talking of an economic boom ahead, but only a baby boom? Or is this just gratuitous, spiteful, anti-American wishful thinking?

We just don't know. This is what happens when a news organisation squanders its reputation for getting the facts right.

Presumably this is the same Nick Bryant who recently accused the US Government of “richly embroidering” the Jessica Lynch story.

And we know that this is the same BBC that is currently in disgrace with everyone who cares about standards in journalism and in public service.