In the wake of basketball star and father-of-four-daughters Kobe Bryant's death, #GirlDad has gone viral on social media with fathers sharing the unique joy of raising daughters. However, in many parts of the world, fewer girls are born than boys today because of sex-selective abortion.

Demographics experts say that "large-scale female feticide" has also occurred in the U.S. in the last decade, in a new analysis published Jan. 27.

"These new data are worrisome, if not alarming-for they demonstrate that large-scale female feticide has been taking place among certain U.S. sub-populations over the past decade," researchers Nicholas Eberstadt and Evan Abramsky found when they looked at U.S. birth statistics.

"The 'global war against baby girls' has opened a front in the United States of America," they said.

The phenomenon of mass female feticide in Asia over the last 40 years has been driven by easily available or unconditional abortion access, cultural preferences for boys, and inexpensive prenatal gender determination technology, Eberstadt explains.

While the natural biological sex ratio at birth hovers around 103-105 boys born for every 100 baby girls, in China and India the ratios hit 115 and 111 respectively in 2017.

With the sex ratio skewed in the two most populous countries in the world, sex-selective abortion accounts for millions of "missing baby girls" each year.

Eberstadt and Abramsky's 2020 analysis also found unnatural imbalances in sex ratios at birth in the U.S. among foreign-born mothers from China and India.

Among foreign-born Chinese mothers, more than 110 boys were born for every 100 girls in the U.S. between 2014-2018. For the third child born, this figure jumps to 122.8 for Chinese foreign-born mothers and 115.3 for Indian foreign-born mothers.

The researchers conclude this can be understood as approximately 8,400 "missing" births of newborn girls in the U.S. from Chinese and Indian mothers between 2014-2018, while the exact number of sex-selective abortions that occurred among those sub-population groups is unclear.

Eberstadt and Abramsky said that they found "some measure of reassurance" in that there was  no conclusive evidence that the same sex ratio at birth (SRB) exists among Asian-Americans born in the U.S.

The abnormal trend only applies to foreign-born mothers from China and India, countries with "mass female feticide."

This week over 100,000 people have posted photos of fathers and daughters on Instagram with #girldad in tribute to Kobe Bryant, who was the father of four girls. Bryant and his daughter Gianna died in a helicopter accident Jan. 26, along with seven others.

The trend was sparked by ESPN analyst Elle Duncan, who shared a memory of a conversation with Bryant.

She said that she had asked Kobe Bryant if he wanted more children, even if there was a chance of having another girl, and said Bryant replied, without hesitation, "I would have 5 more girls if I could. I'm a girl dad."

Following the episode of Sports Center, professional athletes posted photos of themselves and their daughters online with #GirlDad, fathers across the globe followed suit.

"This is trending nationwide because there's no greater or more significant relationship than that of a dad and his daughter(s)," Duncan wrote on Twitter Jan. 28 with a post that linked to the thousands of family photos shared with her in the past few days.

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