The age at which a woman contracts marriage has also to this extent an influence upon her fertility, inasmuch as it appears that those who marry very young are far less fertile than those who marry between the ages of 20 and 25 years; the latter moreover have, on the average, a shorter time to wait for their first conception than women who marry before the age of 20. Women who marry after the age of 25 have to wait longer after marriage for their first delivery; in fact the older the woman after 25, the greater, on the average, the interval between marriage and the first delivery.
Arranging the data already referred to, regarding 556 fruitful women, in relation to this point of view, it appears that the first birth ensued:
| Within 10 months of marriage. | 10 to 15 months after marriage. | 15 months to 2 years after marriage. | 2 to 3 years after marriage. | More than 3 years after marriage. | |
|---|---|---|---|---|---|
| In 163 women marrying at ages 15 to 20 years | 36 | 53 | 46 | 18 | 10 |
| In 313 women marrying at ages 20 to 25 years | 98 | 113 | 56 | 32 | 14 |
| In 70 women marrying at ages 25 to 33 years | 18 | 30 | 12 | 9 | 1 |
| In 10 women marrying at ages over 33 years | 4 | 3 | 1 | 1 | 1 |
To give percentages, the first birth occurred,
| Within 10 months of marriage. | 10 to 15 months after marriage. | 15 months to 2 years after marriage. | 2 to 3 years after marriage. | More than 3 years after marriage. | |
|---|---|---|---|---|---|
| Women marrying at ages 15 to 20 years, in | 22.0% | 32.5% | 28.2% | 11.0% | 8.1% |
| Women marrying at ages 20 to 25 years, in | 31.3% | 36.1% | 17.8% | 10.2% | 4.4% |
| Women marrying at ages 25 to 33 years, in | 25.7% | 42.8% | 17.1% | 12.8% | 1.4% |
| Women marrying at ages over 33 years, in | 40.0% | 30.0% | 10.0% | 10.0% | 10.0% |
Thus whereas in women who contracted marriage between the ages of 15 and 20 years, only 54.5% were confined for the first time within 15 months after marriage, in women who contracted marriage between the ages of 20 and 25 years, in 67.4% the first delivery occurred within 15 months of marriage. And whereas in those who married at the earlier age, the percentage of first deliveries occurring between 15 months and 2 years after marriage was 28.2, in those who married between the ages of 20 and 25, the percentage of first deliveries after the stated interval was only 17.8.
The figures compiled by Whitehead and Pfannkuch give similar results. Of 700 women who married between the ages of 15 to 20 years, there were 306 only who gave birth to a child within the first two years after marriage; whereas of 1,835 women who married between the ages of 20 and 25 years, no less than 1,661 gave birth to a child within two years after marriage—a percentage of 43.7 in the former case, and 90.6 in the latter case. Pfannkuch, as the result of a very large collection of figures relating to this question, found that in women marrying before the age of 20 years, the average number of months before the first delivery was 26; whereas in women marrying after the age of 20 years, the average number of months before the first delivery was 20.
According to Matthews Duncan
| Of Every 100 Women Who Marry | There Become Mothers | |
|---|---|---|
| In the 1st year of married life. | In the 2d year of married life. | |
| Between the ages of 15 and 20 years | 13.71 | 43.70 |
| Between the ages of 20 and 25 years | 18.48 | 90.51 |
| Between the ages of 25 and 30 years | 12.41 | 75.80 |
| Between the ages of 30 and 35 years | 11.44 | 62.93 |
| Between the ages of 35 and 40 years | 9.27 | 40.97 |
Sadler examined the relationship between the age at which marriage was contracted and the number of offspring in the case of the wives of English peers. He obtained the following results: