Some countries have a preference for male children. In others, women die from childbirth and/or exploitation a lot.
Human sex ratio is a tricky business. I guess we'll have to start at the beginning...
Ok, first of all fertilisation is by no means equal and also actually quite variable.
I could go over the messy details with you (and explain how Mary Roach's Ted talk was a ridiculously ill-informed strawman) but it suffices if you merely appreciate that the ratio of male fertilisation generally goes up when a population's health and well-being improves (particularly that of young women obviosly).
Secondly, fetuses are not equal either. Male fetuses are bluntly put more fragile and more succeptible to negative environmental influences. They are also more likely to be defective in some way, which can be remedied by some socities more often than others. Again: As a population's health and well-being increases so does the ratio of male births.
Obviously in some countries active selection is an issue (looking at you, east Asia).
None the less if you look at sex ratios at birth in global comparison you will notice a pretty strong trend.
On the one hand, right up there with China you have the likes of Luxemburg and New Zealand.
By now virtually every country on the planet has more male than female births. A good ball-park number for the parts of the developed world with functioning universal healthcare would be 106/100.
The bottom of the list would be - you could have guessed it - placwes like Haiti and Zimbabwe at virtual parity.
There are still occasionally cohorts born in which females outnumber males, mostly in famines and really ugly civil wars. Darfur may be a candidate.
On the other hand if you look at particular classes of people in developed countries (educated, wealthy, a culture of treating women well doesn't hurt either) you can easily find sex ratios at birth up to 110 and beyond.
Then, obviously people are not equal once they are born either. And not necessarily because anybody has bad (read: sexist) intentions.
Male infants are a lot more susceptable to a wide variety of health problems, which - again - can be remidied in highly organised wealthy societies, but leads to a nearly complete "correction" of the (comparitively small) male surplus at birth in many places in Africa.
In others, women are exported to neighbouring countries as slaves, maids, prostitues or a combination of two or three of those.
The countries that are most prominent for a) young adult women leaving voluntarily or b) young adult women being made to leave in one of the fashions you mentioned are the very ones that have the most pronounced surplusses in female population in general and among young adults as well.
A particular factor in many of these countries (former communist utopias) is gender in education: Ukraine is cranking out more female college graduates than Germany every year, at roughly half the population.
And for the countries with the highest male surplusses among adults it's not so much about sex selection in newborns as much as about migration, too.
Typically these are the countries that attract male migrant workers, who live, work and die in abject conditions, one of which would be not being allowed to bring their families.
Hooray for having the world cup in one of these glorious societies btw...
Anywho, these are the maps you guys were probably looking for (from the very same wikipedia entry as the one strijder posted):
Total population (compared to the global average of 101 per 100).
Population below age 15 (compared to the global average of 106 per 100).
