An estimated 210,000 girls may have “gone missing” due to China’s “Later, Longer, Fewer” campaign, a birth planning policy predating the One Child Policy, according to a new study led by Stanford Health Policy researchers published by the Center for Global Development.

The study looked at hundreds of thousands of births occurring before and during the “Later, Longer, Fewer” policy to measure its effect on marriage, fertility, and sex selection behavior. The policy, which began in the 1970s and preceded China's One-Child Policy, promoted later marriage, longer gaps between successive children, and having fewer children to cut the country's population. The study emphasizes that because this policy existed before ultrasound technology was widely available — and therefore before selective abortion was an option — these missing girls must have been due to postnatal neglect of infant girls, or in the extreme, infanticide.

The authors of the new study are Grant Miller, director of the Stanford Center on Global Poverty and Development, a core faculty member at Stanford Health Policy and senior fellow at the Freeman Spogli Institute for International Studies; Kimberly Babiarz, a research scholar at Stanford Health Policy; Paul Ma and Shige Song.

The researchers found that China’s “Longer, Later, Fewer” population control policy reduced total fertility rates by 0.9 births per woman and was directly responsible for an estimated 210,000 missing girls countrywide. The phenomenon of “missing girls” widely recognized in later years under the One Child Policy is largely thought due to sex-selective abortion after ultrasound technology spread across China.

“Prior research has shown that sex ratios rose dramatically under China's One-Child Policy, leading to stark imbalances in the numbers of men and women. But we’re finding that girls went missing earlier than previously thought, which can in part be directly attributed to birth planning policy that predates the One-Child Policy,” said Grant Miller, a senior fellow at the Stanford Institute for Economic Policy Research and a non-resident fellow at the Center for Global Development.

The top findings of the study include:

• The birth planning policy reduced fertility by 0.9 births per woman, explaining 28 percent of the overall decline during this period.

• The Later, Longer, Fewer policy is responsible for a roughly twofold increase in the use of “fertility stopping rules,” the practice of continuing to have children until the desired number of sons is achieved.

• The Later, Longer, Fewer policy is also responsible for an increase in postnatal neglect, from none to 0.3 percent of all female births in China during this period.

• Sex selection behavior was concentrated among couples with the highest demand for sons (couples that have more children but no sons), with sex ratios reaching 117 males per 100 female births among these couples.

“Population control strategies can have unforeseen consequences and human costs,” Miller said. “At the same time, as China debates the future of birth planning policies, it’s also important to note that family planning policy does not appear to be the largest driver of fertility.”