There's a fine article at Spiked by Tim Black exposing
what Robert* Malthus actually said. Malthus was a reactionary
nostalgic pessimist who was not just wrong about population growth
outstripping food supply. He was also wrong in his cynicism about
helping the poor lest they breed more.

(*Everybody calls him Thomas these days, whereas his
contemporaries all called him Robert, which was his second name.
Calling him Thomas is like calling the first director of the FBI
John Hoover.)
His subject was not so much the principle of
population growth - this Malthus was happy to take for granted,
hence the scant attention he actually paid to justifying it.
Rather, his real purpose was the extent to which a supposed law of
population would confound those writers like Godwin and Condorcet
who advocated social transformation. The theory, the so-called
science, was always subservient to Malthus's main objective of
justifying the social order as it is. As Malthus
himself wrote: 'The principal argument of this Essay only goes to
prove the necessity of a class of proprietors, and a class of
labourers.' Malthus was not pessimistic about the chances of
improving society because of his theory of population - that is the
wrong way round. His wilful social pessimism, where misery was the
lot of the majority, inspired his theory of population.
...The Essay is at the very
least a striking attempt to smother society as it then was in
amber, to fix it permanently in time. The forces that would
revolutionise society, from the burgeoning industrial bourgeoisie
to the incipient class consciousness of the proletariat, threaten
Malthus's world on either side. He wants to hold these social
forces back, to paint them as tending against the natural order of
things. This was what was always animating the essay, not some
scholarly concern with population growth and agricultural
productivity: a desire to render society, in all its vice and
misery, as the product of the laws of nature.
The Essay was a stunning work of reaction, a
desperate rear-guard move from a man who, at some level, knew the
tide of history was rushing against him. For there is nothing more
desperate than blaming hunger and want on the excessive breeding of
the 'race of labourers'.
Today's neo-Malthusians generally think of themselves as leftish
progressives. But their hero was a dogmatic conservative. There is
a pattern here. Neo-Malthusians also tend to hero-worship Garret
Hardin, the author of "The Tragedy of the Commons" article in
Science (1968).

I met Hardin once and found him a reactionary anti-immigration
conservative. So I went and read the famous article right to the
end, which I had not done before and was shocked to find that its
famous bit, about the mismanagement of common property, is just a
brief prelude to a diatribe about coerced population control:
Coercion is a dirty word to most liberals
now, but it need not forever be so. As with the four-letter words,
its dirtiness can be cleansed away by exposure to the light, by
saying it over and over without apology or embarrassment. To many,
the word coercion implies arbitrary decisions of distant and
irresponsible bureaucrats; but this is not a necessary part of its
meaning. The only kind of coercion I recommend is mutual coercion,
mutually agreed upon by the majority of the people affected.
The most important aspect of necessity that
we must now recognize, is the necessity of abandoning the commons
in breeding. No technical solution can rescue us from the misery of
overpopulation. Freedom to breed will bring ruin to all. At the
moment, to avoid hard decisions many of us are tempted to
propagandize for conscience and responsible parenthood. The
temptation must be resisted, because an appeal to inde- pendently
acting consciences selects for the disappearance of all conscience
in the long run, and an increase in anxiety in the short.
The only way we can preserve and nurture
other and more precious freedoms is by relinquishing the freedom to
breed, and that very soon. "Freedom is the recognition of
necessity"-and it is the role of education to reveal to all the
necessity of abandoning the freedom to breed. Only so, can we put
an end to this aspect of the tragedy of the commons.