Whether or not WuDunn is underplaying the numbers, her solution given in the second major tenet is bound to perpetuate the problem:
The second tenet of "Half the Sky" is that, let's put aside the morality of all the right and wrong of it all. And just on a purely practical level, we think that one of the best ways to fight poverty and to fight terrorism is to educate girls and to bring women into the formal labor force. Poverty, for instance. There are three reasons why this is the case. For one, overpopulation is one of the persistent causes of poverty. And you know, when you educate a boy, his family tends to have fewer kids, but only slightly. When you educate a girl, she tends to have significantly fewer kids.
I believe WuDunn may be deliberately underplaying the number of missing girls because it would affect public perception of the above agenda. That agenda, as a practical matter, requires the widespread availability and practice of abortion. The case for the link between regular use of artificial birth control and abortion has been made elsewhere so I will not rehearse it here. In order to bring women into the formal labor force and keep them there, you have to depend upon abortion when contraception fails. Abortion is the birth control back-up plan, so to speak. So, yes, let's put aside the morality of it all, shall we?
[As an interesting aside, I have been criticized elsewhere for linking WuDunn with Mao and calling her a fan of Mao which is odd when you consider that only when the communists were moving women into the formal labor force did Mao coin his now famous phrase, "Women hold up half the sky." And what is a major focus of her agenda? Moving women into the formal workforce!]
I believe there are tell-tale signs all the way through this talk that WuDunn doesn't really love these people, she just thinks they need her. One sign was the way she depersonalizes people in references like this, "the breast shows no son preference." Another was that obvious instance where she urged us to put aside morality in favor of her agenda because she knows how to help these people. But the most egregious instance is her parroting of the overpopulation myth which brings me to the reason for this extended introduction.
Steven Mosher is a widely recognized authority on population issues, particularly in China. The first American social scientist allowed in China, he witnessed the coercive methods of enforcing the "One Child" policy from the first days of its existence. Mosher heads up the non profit, Population Research Institute which, "works to end coercive population control, and fight the myth of overpopulation which fuels it."
Of their special projects, Overpopulation is a Myth is just chock full of catchy videos and the science to back them up. Other projects aim to Stop Sex-Selective Abortion and Project Real Need which aims at stopping the flow of tax dollars to funding abortion and put that money where it is needed, such as in Malaria prevention measures.
So tour around PRI, get to know their work and check out some of the videos. You will come away understanding that overpopulation is far from being a "persistent" cause of poverty, it is a myth. And forget WuDunn's amoral prescription.
*please also read some additional information in the first comment.