Friday 26 March 2010

North-South divergence on births

The Central Statistics Office (CSO) yesterday published its bulletin on vital statistics for the third quarter of 2009 (in the south), and it shows some differences between the north and the south.

The figures for 2009 for the north, published by NISRA on 18 March show that the birth rate (the number of babies per 1000 of the population) was 13.9 – and this represented a slight decrease from 2008. In the south, by contrast, the birth rate was a whopping 17.3 – an increase from the previous year, and by far the highest rate in the EU.

In fact, the birth rate in the south is usually higher than the north, and they tend to move in roughly the same direction:

In 2009, though, they moved in different directions, and a considerable gap has thereby opened up.

Reasons for this divergence are not obvious. The increasing birth rate in the south, as in the north, can be partly ascribed to the influx of young migrants since the opening up of both labour markets to A8 workers in 2004. This has had the effect of lowering the average age in the population, but more importantly, of adding a large group of people of prime child-bearing age to the population. So far, so obvious – the number of births increases, and the birthrate increases with it. But why did this change in 2009? Babies born in 2009 would probably represent decisions taken nine months earlier – thus usually in 2008, when times were not so bad (compared with now). Were expectations in the north in 2008 worse than in the south?

This scenario is not borne out by the evidence of the labour market – unemployment rates in the north did not deteriorate compared with the south in 2008-9. So why did people continue to have babies in the south, but hold back in the north? These questions cannot be easily answered, and probably require some additional research to be done.

Another question that the figures pose is 'why is the southern birth rate generally higher than the northern birth rate?'

Here, perhaps the answer is easier. The population of the south is younger – only 11% was over 65 (in 2006), against 14% in the north (in 2008). In addition, in the north 23.6% of the population was aged between 45 and 64, whereas in the south this cohort represented only 21.9% of the population. This means that almost 38% of the north's population was over the normal reproductive age, while in the south less than 33% was. Clearly, with more people at reproductive ages in the south there would be more births:

Certainly the higher proportion of the south's population in the fertile 25-44 age group explains a large part of its higher birth rate – but even if births in 2009 in both jurisdictions are expressed as a rate per thousand of the population size in that age group the south appears to be more fertile:

  • South – 1,345,873 people aged 25-44– 77,156 births* = 57.3 per thousand
  • North – 492,721 people aged 25-44 – 24,900 births = 50.5 per thousand

[*2009 Q3 figures multiplied by 4]

A third and slightly more complicated question can also be posed: does the lower northern birth rate imply a lower fertility in the Catholic community in the north than amongst their cousins in the south? Figures for the Total Period Fertility Rate (the hypothetical number of children the 'average woman' will have in her lifetime) for the south for 2009 are not yet available, but in 2008 the TPFR was 2.1 (a slight increase from 2007's 2.0).

In 2009 the TPFR in majority-Catholic areas of Northern Ireland tended also to cluster around 2.1, while in majority-Protestant areas the TPFR tended to be lower (areas not included tend to be fairly closely balanced at child-bearing age):
So, to answer the third question, the evidence seems to imply that (cultural) Catholic fertility is similar north and south, and thus that the lower birth rate in the north may be due to a lower fertility amongst (cultural) Protestants.

Nothing yet answers the first and most puzzling question – why the birth rate in 2009 headed in different directions in the two jurisdictions? Perhaps an answer will become obvious over time, or perhaps 2009 was simply an unexplainable anomaly. This blog will continue to watch these statistics to see if an explanation presents itself.


New times, New approach said...

Time could prove me wrong (as indeed it can prove anything wrong - see flat earth at centre of universe and the ethical morality of churches and politicians) but I would be more inclined to see this as a statistical aberration.
Look back at 2001/2002 and the chart will show a not dissimilar situation whereby the North's fertility rate proceeded sharply downwards while the South's climbed. This was then reversed in 2003 when the South's stabilized, then fell and the North's rose.
Have you investigated the typical fertility rate of the immigrant community? I am sure the South (Celtic Tiger as was) would have presented as a much more attractive destination than the North with it's dreary steeples and forever sucking Britain's economic hind tit. If they had a higher fertility rate (and would predominantly have been in the 25-44 age grouping) then this might help explain the differential.
Also as the South remains an economic basket case which will inevitably stimulate racism (why do they allow foreigners to take our jobs etc. etc.) then those immigrants will move elsewhere, which will result in a drop in birth rate (provided my presumption of their greater fertility is correct).
So I would be rather surprised if this heralded a substantial ongoing divergence.

Mack said...


I'm not sure immigrant TPFR's would be high enough above or below those of the locals to make a huge difference. TPFR's have fallen massively across the globe and are much lower than in Ireland in many of the immigrants home countries (Eastern & Southern Europe especially).

Immigration & emigration would make a big difference to the raw birth rates as migrants tend to be of child bearing age (e.g. simple example, a population of 1000 has 15 births, 4 immigrant couples arrive had have 2 children, the ratio is now 17/1008 (16.9 approx).

As such raw birth rates can not only highlight age structure differentials but also net migration trends.

Anonymous said...

The divergence is because so many people (without babies) emigrated from the 26 counties last year, causing the base to fall and the ratio to rise.

Mack said...

Anon -

Most of the emigrants out of Ireland would be child bearing age. If you reverse the example, let's say you have a population of 1000 that would have 15 kids. Job loses mean that 50 couples leave, 2 of which would have had children otherwise. You get 13/1000 = a birth rate of 14.4 - a fall.

Higher net emigration in the south should cause the birth rate there to fall relative to the birth rate in the north rather than rise.

An age differential between emigrants and immigrants could make a difference. E.g. if emigrants out of Ireland tended to be younger than immigrants coming in (or if the immigrants culturally have kids at a younger age) - the new arrivals could push the birth rate up further than the leavers depress it.

E.g. In the above example 40 new couple arrive come and have 2 babies, now were at 15/990 which is a birth rate of 15.1 - a birth rate rise.

Anonymous said...

How many of those births are ethnic Irish?

Anonymous said...

"The divergence is because so many people (without babies) emigrated from the 26 counties last year, causing the base to fall and the ratio to rise."

Um.. take a look at the graph, the line representing birth rates in the south is simply continuing it's historical trend upward, it is the North which has statistically changed compared to previous years.

Your suggestion would only work if there were factors that lowered the birth rate across the entire island and the emigration from the South was great enough to still actually register as an increase in birth rate.

Extremely unlikely, especially considering emigration from the Republic has been grossly exaggerated, neither the Irish nor immigrants are emigrating in any large numbers, in fact immigration/emigration in the south is pretty equal at the moment.

hoboroad said...

ridingBYriding said...

No offence, but this post clearly shows bias. You take one datapoint, 2009, and attempt to draw from it a huge and new trend that will continue to the end of time. Look at 2002. Now look at 2004. You cannot take a single datapoint and draw conclusions as radical as you have from it. Don't get me wrong, I support a united ireland, and I think the catholics have gotten the shaft by british protestants not only in britain and ireland, but all over the world where the two exist together; but you are grasping at straws here to attempt to justify your bias.

hoboroad said...

hoboroad said...