Investigating the late fertility transition in with individual data on a long-living population (Villagrande, 1851-2012)

Michel POULAIN1,2, Anne HERM1,2, Dany CHAMBRE and Gianni PES3

1 Estonian Institute for Population Studies, Tallinn University, Estonia 2 IACCHOS, Université catholique de Louvain, Louvain-la-Neuve, Belgium. 3 Department of Biomedical Sciences – Università degli Studi di Sassari -

Please do not quote this contribution and use its results before publication

1. Questions addressed

How the survival of children (infant and child mortality) may affect the fertility behaviour of their mother? This question is important in the study of the impact of the reduction of infant mortality on the fertility transition.

2. The context and the choice of the population investigated

Sardinian late fertility transition and high level of marital fertility has been reported by numerous researchers (Livi Bacci 1977, Bernardi 2007). Still in 1950’s the province of in the mountainous part of Sardinia showed the highest values for the Coale Index on marital fertility Ig among all Italian provinces during the fertility transition (figure 1). Sardinia as whole but more specifically some in-land regions of the island, mostly in the Nuoro province, were still recently characterised also by late maternity (Astolfi et al. 2007, 2009).

3. Setting, data and methods

The village of Villagrande is located at 700 meters above sea level in the . On 1 January 2010, 3,441 inhabitants lived in Villagrande (ISTAT) with agro- pastoral activities and traditional life style still prevalent.

Demographic genealogical data on the whole population of the village has been collected. The start and end points of the database as marked by earliest birth included and last deaths ranges from year 1826 up to 2012. The families have been reconstructed for couples that registered their civil marriage in Villagrande starting 1851 up to 1955. A total of 1067 family nucleus composed by a couple having at least one child were reconstructed including 5788 children. We identified 702 women that are mothers in completed families in a sense that both spouses marry only once and both survived up to the end of the fertility period of the mother. For 87 women alive on 1st January 2012, the data will be right-truncated.

4. Fertility transition in Villagrande

Fertility levels and trends could be estimated by using Coale’s index with data on the number of children born and mothers at risk extracted from the family database. The computed Ig are compared with similar data for the province of Nuoro, Sardinia and Italy (figure 1). These trends confirm that the population of Villagrande is experiencing higher fertility rates and a very late fertility transition as the TFR only decreases after 1950.

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*Data from Livi Bacci (1977) p. 66 ** Data from Livi Bacci (1977) p. 141

The Villagrande family database allows computing marital fertility rates by age group of mothers up to 1950 and figure 2 shows that the fertility level of women above 35 years start to decrease only in the 1930’s.

Figure 2. Marital fertility rates in Villagrande by five years age groups from 1870-1960 (mobile average on 11 years).

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!"!# %()(# %(((# %(,(# %,!(# %,%(# %,&(# %,'(# %,*(# %()!# %()&# %()*# %()+# %((!# %((&# %((*# %((+# %(,!# %(,&# %(,*# %(,+# %,!!# %,!&# %,!*# %,!+# %,%!# %,%&# %,%*# %,%+# %,&!# %,&&# %,&*# %,&+# %,'!# %,'&# %,'*# %,'+# %,*!# %,*&# %,**# %,*+# %,$!# %,$&# %,$*# %,$+# %-,$(# %-,+!# The age of first child does not show any specific trend while the age at last child decreases significantly for the generations of mothers born after 1890, corresponding of births occurring after 1930. The total number of children per mother increased for mothers born in the second half of the XIXth century and decreased for generations born after 1900 for which children were born after 1930.

We observe remarkable delay of the end of the reproduction period among Villagrande married women. The mean age of women at the birth of the last child in completed families was above age 40 for all generations of mothers born until 1910. Similar data for Alghero in 1866-1885 show more than 2 years earlier end of fertility for women. Also data from AKEA study on Sardinian centenarians born between 1900-1905 show lower average age of mothers at birth of first and at last child compared to the same birth cohorts in Villagrande. According to Caselli et al. (2012) the mean age of mother at first birth among Sardinian female centenarians was about 27 years and at last child 39 years while in Villagrande for cohorts born in 1900-1910 the latter was 40.5 years.

Infant and child mortality

The probability to die before 5 years varies largely around 25 et 30% up to 1930. From then to 1965, the fall is clear to reach about 5%. These changes present large differences between infant and child mortality. Infant mortality was never high (more than 15%) in Villagrande and this cannot be explained by non-registration of children who died in their first days of life. The distribution of the length of intergenesic intervals does not indicate the existence of missing children while children recorded exactly with those found in the church baptism register for the years 1866-1875. The infant mortality is declining starting from 1930 and the decrease is from 13% à 5% in 30 years up to 1960. The child mortality was largely higher between 1870 and 1880 (about 20%) but it decreases to stay between 10% and 15% up to 1920. Then the decrease was permanent up to 1% from 1955.

5. Interaction between fertility and mortality investigated at individual level

Is the probability to give birth to an additional child influenced by the survival of the previous one? More globally what is the impact of the decrease in infant mortality on the decrease in fertility during the fertility transition.

In order to investigate this question we consider three groups of mothers and we consider their probability to have a new child starting at the time of the previous one: • in natural fertility regime when the previous child was born up to 1930; • in an early transitional phase for previous child born between 1931 and 1950; • during the transitional phase in itself for previous children born between 1951 and 1965.

When controlling by age groups of mother, the results of the Cox regression shown in Table 1 present relative fertility risks for mothers who lost their previous child that are significantly higher than 1. Even if this relative risk decreases during the fertility transition phase, it is still as high as 1.843 for the third group of mothers.

Accordingly if the infant mortality decreases the fertility should do the same as the need to give birth to babies replacing the lost ones decreases.

Table 2. Relative risk to have another child after the birth of the previous one for mothers distributed in three groups according the period of birth of the previous child.

Year of birth of previous child 1866 - 1930 1931 - 1950 1951 - 1965 Number of cases 3021 1241 889 Number of previous 391 115 50 child who died before 12 months Proportion (A) 12,9% 9,3% 5,6% Total fertility rate (B) 8.40 8.17 7.62 Covariates in Cox regression Mother age group 20- 1 1 1 24 25-29 0,869*** 1,064 0,832 30-34 0,714*** 0,905 0,724* 35-39 0,417*** 0,461*** 0,505*** 40-49 0,098*** 0,134*** 0,141*** Previous child 1 1 1 survived Previous child died 2,342*** 1,790*** 1,843*** before 12 months (C) Estimated TFR in 7,16 7,61 7,28 absence of infant mortality B / ((1-A) + A*C)

In conclusion, even if we observe that mothers losing one child have a lower over risk to have a new child during the transitional period compared to the period of natural fertility regime, the decrease of fertility is lower that what could be expect from the decrease in infant mortality. In fact the fertility level for mother without lost child increased in the first phase of the transition between 1931 and 1950 and started to decrease thereafter only. As shown on figure 11, the contribution to the observed TFR from mothers without lost child increased in the first phase and stay stable thereafter while the contribution of those losing their child is largely decreasing.