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Effects of Abortion on the U.S. Population

In 1973, the Supreme Court addressed the issue of abortion in two cases, Roe v. Wade and Doe v. Bolton. The Court’s holding in Roe and Doe had the effect of legalizing abortion on demand through all nine months of pregnancy. Prior to the federal legalization of abortion, states had the authority to independently determine abortion’s legality. Although states could still impose restrictions in the second and third trimesters of pregnancy, 1973 marked the year in which all states were required to legalize abortion.

Roughly 53 million abortions were reported between 1973 and 2011. The Guttmacher Institute estimates that there were 1.1 million abortions in 2011 (the lowest yearly rate of abortions in the U.S. since 1973).

U.S. Abortion Rate, 1973-2011

Legalizing abortion massively changes sexual behaviors outside of marriage. The consequent sexual revolution increases conception out-of-wedlock and causes venereal diseases. In a country of a few million births per a year, these increases themselves approach the millions. The additional disease transmission vector comes with a cost around $300 million annually, paid collectively by individuals and through taxes.

1. Legalizing Abortion Changes Sexual Behavior

Abortion affects sexual activity. Whereas previously the expected consequence of sexual activity–conception and birth–previously discouraged sexual behavior (particularly outside of marriage), the legalization of abortion removed the consequence of childrearing and therefore increased sexual activity. The availability of a new option to abort one’s child has resulted in a greater number of children being conceived than there would have been had sexual behavior retained the normal result of a child being born.

According to the Center for Disease Control, 15 percent of children aborted were children of married mothers while the remaining 85 percent of children aborted are the children of unmarried mothers. Eighty-five percent of abortions are by unmarried mothers. These unwed mothers changed their sexual behavior.

At most, all 15 percent of abortions by married mothers are conceptions that would not have occurred had abortion not been legalized. Similarly, the abortion rate before legalization was roughly 10 percent of what it became after legalization. Sixty-six percent of abortions are conceptions that would not have occurred but for changed sexual behavior. This means at least 40 percent of abortions are conceptions by unmarried women that occur as a result of sexual activity that would not have occurred without abortion legalization.

Legalizing abortion increases sexual behavior outside of wedlock. Around 600,000 children—40 percent of 1.5 million abortions, and around 15 percent of the total number of births (4 million)—are now destroyed annually on account of being conceived out of wedlock because abortion was legalized. This is a massive social and ecological effect abortion has on sexual behavior. Legalizing abortion creates a massive amount of new out-of-wedlock conceptions that will then be destroyed.

2. Effects of Abortion on the Birthrate

The effect of abortion on birthrate is not simply the raw number of reported abortions; rather, abortions reflect both births that would have otherwise taken place, and children that were only conceived because of how abortion changes society. The total number of abortions minus the number of children that would not have been conceived absent the legalization of abortion better indicates the effect of legalized abortion on the birthrate.

Since abortion has resulted in increased sexual intercourse, and hence in increased conception, researchers must isolate the number of pregnancies that would not have occurred if abortion had not been legalized. It is first necessary to determine the impact of abortion on total births. Then, by determining this impact of abortion, the percentage of aborted children that otherwise would not have been conceived can be determined.

Prior to the ruling in Roe v. Wade, states individually determined the legality of abortion. This phenomenon of these states individually legalizing abortion (at different times) creates a natural experiment. This experiment shows that the greater the distance from the closest early legalizing abortion state, the less likely a woman is to abort her child. This natural experiment then shows that legalizing states experience a 10 percent decline in birthrate compared to non-legalizing states far away. Early legalizing states demonstrate the direct effect of abortion on birthrate. Non-legalizing states far away serve as a kind of control group for abortion’s impact on birthrate.

From the 1970s through the 2000s the number of live births averaged approximately four million per year. While over this period the U.S. population has increased, the fertility rate (birthrate) in the U.S. has decreased per (fertile) adult. An increase in the U.S. population has compensated for the per adult decrease in fertility. The “natural experiment” among the states shows that abortion causally reduces births by around 10 percent. Had abortion not been legalized, approximately a third of aborted children would be present today.