Who would be considered "poor", however? Unemployed individuals, or simply low-earning ones, and in which country? Giving the declining birth rate in first-world countries, reducing reproduction in rich countries would further increase the population imbalance between rich and poor countries.
It must also be asked, is improving equality a goal worth pursuing? You could improve equality by making every single individual dirt-poor. Improving average living standards would be a better in my world-view - and by all metrics, that has been going up since the start of the industrial revolution.
Birth rates almost invariably go down as a society gets richer and more educated - therefore the goal of improving average welfare could be better served by improving the lives of third-worlders directly, which would naturally decrease their birth-rates in the long-term.
Another argument could be that many "poor" individuals have positive economic impact - they are consumers of goods increasing overall economic output, or provide useful labor at a low price, allowing many others to have goods and services they could not otherwise afford.