Forty years ago I wrote a young adult book entitled Conception, Contraception: A New Look. It details the miracle of conception and explores humanity’s millennia-long search to understand its mystery. The book was also meant to alert young readers to the problem of overpopulation. Though it was not a success, the book has always been one of my favorites. It was “born” at a time when the topic of birth control were considered unfit for high school students.

It was Anton von Leeuwenhoek, the Dutch inventor of the microscope, who first saw the human sperm in 1674. In 1827, another 150 years later, Karl Ernst von Baer finally identified the mammalian egg, thereby cracking a problem that, in his words, “had been discussed ad nauseum in every textbook of physiology as insoluble.”

As a medical writer I was fascinated in the science behind all that, but my aim in researching and writing the book was overpopulation. To an overwhelming extent all our troubles can be traced to the fact that there are simply too many of us to share and enjoy our beautiful earth. Thomas Malthus, an English scientist, was one of the earliest to write about it convincingly in 1798, and we are reminded daily of the accuracy of his predictions.

Agnes Gillot, my 15-year old downstairs neighbor in Brooklyn Heights, discovered the threat of overpopulation while surfing the net. Coincidentally her mother had purchased my long-forgotten book from Amazon.com. It inspired Agnes to devote her spring term paper at Saint Ann’s School to overpopulation.

Birth control and overpopulation are like the two sides of the same coin. Attempts at avoiding unwanted birth are as old as mankind itself. Egyptian papyri already recorded a few crude barrier methods and many ineffective other means. Effective contraception dates from the beginning of the twentieth century. Margaret Sanger is America’s heroine of birth control. From the time she was a child she observed that economically comfortable, happy families had fewer children, whereas poor families, like hers, had large families. Moreover, she blamed her mother’s early death on her relentless childbearing.

Sanger became a nurse. She was abhorred by the deaths resulting from illegal and self-inflicted abortion. After she watched her patient Nellie Sachs die, she resolved to teach women the then-available methods of contraception. In 1916 Sanger opened a birth control clinic in Brownville, Brooklyn. The clinic was closed and Margaret went to prison, but eventually her efforts bore fruit. Then and now abortions performed by trained practitioners became relatively safe, and today effective methods of birth control are available. At long last the number of abortions performed in the US is decreasing, as is the teen pregnancy rate.

Even so, the timing of pregnancies in the US continues to be a major problem. According to the Guttmacher Institute, half of all pregnancies in the US are unplanned; four in ten resulting in abortion. There were 1.06 million abortions in 2011. The US also has the highest teen pregnancy among major developed countries. About ¾ million women between the ages of 15-19 conceive annually.

I cannot believe that a hundred years after Sanger opened her first birth control clinic we are again, or still, waging the same battles. Currently many states are severely restricting access to legal abortions. Moreover, the inclusion of the cost of birth control in medical insurance plans is under discussion. It stands to reason that, as in Margaret Sanger’s days, the rich will continue to solve their childbearing problems, whereas the poor will again struggle with problems of giving birth to children at the wrong time.

The figures to demonstrate these effects are already in. New Mexico, Mississippi, Texas, Nevada, Arkansas and Arizona, states in which abortion is an issue, have high teen pregnancy rates, whereas New Hampshire, Vermont, Minnesota, North Dakota and Massachusetts, states in which birth control and abortion are less of an issue, have low teen pregnancy rates.