Demographic and epidemiological studies have quantified adolescent pregnancies as follows.

Teenage Pregnancy Rate
This frequency, expressed per 1,000 persons, is the total number of pregnancies (births, abortions and miscarriages) for young women, 10–18 years old, divided by the number of females in this age group.

In France, this rate has been estimated to be 24‰. Only one-third of these pregnancies will be carried to term. According to our inquiry conducted in the Seine-Saint-Denis Department (a northern suburb of Paris with a highdensity population of young immigrants or youths of foreign ancestry), this rate was 50‰.

In Great Britain in 1997, approximately 90,000 teenagers 13–19 years old became pregnant; three-fifths of them were carried to term, i.e., 54,000 births.

In the USA, the teenage pregnancy rate for 15- to 19-year-olds has been estimated to be 96‰. During the 1990s, it was evaluated at 177‰ (essentially black and Hispanic adolescents) and represented the highest rate among industrialized countries. Every year, approximately 1 million American teenagers, 11–19 years old, become pregnant (11% of all girls in this age group). Almost 30,000 girls 11–15 years old become pregnant every year. In most states, birth rates were considerably higher for black teens than for whites. However, between 1992 and 1995, greater declines were reported for blacks than whites.

Today, Hispanics have the highest teen birth rate. Overall, 50% of these adolescents carry their pregnancies to term; 35% opt for an abortion and 15% miscarry or experience in utero fetal deaths.

Adolescent Fertility Rate
In France (1997–2001), this frequency, which represents the birth rate for young women 15–19 years old, was 9.5/1,000; in Seine-Saint-Denis (the French department with the highest birth rate) it was 11.6/1,000, as compared to Great Britain, where it was 34/1,000, and 12/1,000 in Germany and Spain.

In contrast, Sweden and The Netherlands have, by far, the lowest rates, around 2–3/1,000. Even though teenagers in these countries are sexually active at a very young age, the governments are the most motivated. They have developed educational programs to disseminate sex education in schools and the diffusion of contraception, including authorization of publicity in the media. Among developed nations, the USA has the highest fertility rate for this age group: 55/1,000 (almost half choose to maintain their pregnancy and, among them, 90–95% raise their child).

Percentage of Teenage Pregnancies
This value is defined as the number of births to adolescents, divided by the total number of births in a given country. In our French study, we more specifically decided to consider minors (legally defined as girls under 18 years of age) because they present particular problems. In France, the numbers of births to adolescents declined sharply between 1976 and 1992, from 3.6 to 1%. Over the past 10 years, the percentage has stabilized around 0.85%. In our study in Seine- Saint-Denis, it was 1.9%, but this value reflects a recruitment biased by the population of our area. In 1997, 6,356 births in France were recorded for mothers 18 years old or younger; 954 of the mothers were under 16 years of age.

The American rate was estimated to be 13% compared to the total number of births, i.e., 500,000 births to mothers 11–19 years old. In 1995, more than 1,200 births were recorded for mothers 11–15 years old.