Legalised abortion brings welfare spending down
A child born to parents that did not want it is more likely to cost the government money in the form of welfare spending throughout its life.
From the moment of its conception, an unwanted child costs the government more than a wanted child. Having and raising children is financially taxing for families, and in 2004 survey, the Guttmacher Institute reported that 73% of women who had abortions in the US did so because they could not afford to have children. Firstly, a birth procedure costs more in healthcare costs than an abortion. Secondly, since more women from lower economic classes seek more abortions, the child is more likely to grow up impoverished than its counterparts, costing the government more in welfare. Unfortunately, because the child is statistically more likely to be from a lower economic class, it is statistically more likely to be unemployed or involved in crime in its adult life. If the child grows up to become a criminal, it costs the state far more in incarceration costs and legal proceedings. The connection between abortion laws, crime, and public spending was best illustrated by a nationwide study carried out between 1970 and the 1990s. It found that in states that legalised abortion the 1970s, the crime rate had dramatically lowered by the 1990s, 18 years after women could begin legally terminating pregnancies. The study found that simply legalising abortion could cause a decrease in crime by up to 50%. 
Human life should not come down to economics. You cannot put an economic value on human life. Any attempt to do so is inhumane and barbaric. Also, treating abortion this way is tantamount to eugenics and social engineering. Poor people's babies have the same right to life as those of the wealthy. Permitting abortion based on the notion that poor people get more abortions and their children cost the state more is a form of sociological engineering, particularly given that ethnic minorities are overrepresented among the working classes. Finally, the notion that someone from a poor background is likely to be a net recipient from the state is just not true. The average child born into poverty goes on to become a net contributor over the course of their lifetime. In fact, less than 5% of children born into families that receive welfare payments will remain on them as adults. Therefore, abortion does not even make economic sense.
[P1] Abortions are most common among the lower economic classes. [P2] These classes cost the government more in welfare spending than other classes. [P3] Therefore, providing women with access to abortion saves the government money in the long run.
[Rejecting P3] Abortions do not save the government money in the long run. That is a myth.