Don't apologize! It makes sense! Something I know as an American Catholic historian wannabe. So I'm going to attack this in 2 routes: 1 as a religious Catholic historian which will be more theological and 1 as a regular historian, which will get you there but not give you any of the theological background.

So contraception used to be seen as immoral amongst all branches of Christianity. It was seen to contradict Genesis 1:28, when God said "And God blessed them, saying: Increase and multiply, and fill the earth, and subdue it, and rule over the fishes of the sea, and the fowls of the air, and all living creatures that move upon the earth." (Gen 1:28, Douay Rheims). Early Church people, such as St. Jerome in his Letter to Eustochium, were very concerned about contraception as abortion. He claimed Roman women "go so far as to take potions, that they may insure barrenness, and thus murder human beings almost before their conception." (http://www.newadvent.org/fathers/3001022.htm, Article 13). Others, such as St. Augustine, pointed to Onan's troubles in Genesis as proof God was against contraception and that sex and procreation had to be linked (Onan was killed by God for a) not raising a child in his brother's name with his sister-in-law in a process known as levirite marriage and b) practicing coitus interruptus. To past Christians, contraception devalued marriage in a sense by prohibiting God from creating new life through sexual congress.

However, some Protestants were the first to change that. At the 1930 Lambeth Conference of Anglican bishops, Resolution 15 was passed 193 for, 67 against, and 47 present/not voting. What did Resolution 15 do? It said thus.

Where there is clearly felt moral obligation to limit or avoid parenthood, the method must be decided on Christian principles. The primary and obvious method is complete abstinence from intercourse (as far as may be necessary) in a life of discipline and self-control lived in the power of the Holy Spirit. Nevertheless in those cases where there is such a clearly felt moral obligation to limit or avoid parenthood, and where there is a morally sound reason for avoiding complete abstinence, the Conference agrees that other methods may be used, provided that this is done in the light of the same Christian principles. The Conference records its strong condemnation of the use of any methods of conception control from motives of selfishness, luxury, or mere convenience. (http://www.anglicancommunion.org/media/127734/1930.pdf, Page 7, Resolution 15).

So this was new. Previous Lambeth Conferences in 1908 and 1920 condemned contraception in all cases but this Resolution allowed for it in certain circumstances. This lead to overall acceptance and relaxation of norms as it was seen to prevent a bigger evil: abortion. Resolution 16 still condemned abortion. To many theologians, like Jerome and others, abortion was murder and a great evil. So it was the Lambeth Conference for the Anglicans, plus the growth of the modern world and urbanization that contributed to acceptance of contraception.

Now your question. The answer is no. Again, early Christians were afraid of abortificents and the concerns of contraception weakening the marriage. There wasn't an important figure who decreed it, it was seen as something the Church taught. Also, remember, in agricultural and rural societies, children were free labor for the farm. So more hands make lighter work.

But the Church isn't heartless; every sexual act doesn't mean children, but rather remains open to children. In 1930, as a result of Resolution 15, Pope Pius XI issued Casti connubii. This encyclical basically slammed the Anglicans, condemned abortion, and praised marriage as where "the souls of the contracting parties are joined and knit together more directly and more intimately than are their bodies, and that not by any passing affection of sense of spirit, but by a deliberate and firm act of the will; and from this union of souls by God's decree, a sacred and inviolable bond arises." (https://w2.vatican.va/content/pius-xi/en/encyclicals/documents/hf_p-xi_enc_19301231_casti-connubii.html, Article 7). Despite the bonding effect sex brings, Pope Pius XI was clear: marriage was for creating and raising children (same, Article 24).

But during the Second Vatican Council, this issue came up again. And Pope St. John XXIII before dying set up a Pontifical Commission on Birth Control which included bishops and cardinals (such as some guy Karol Wojtyla aka Pope St. John Paul II), but also American, French, and Canadian laity. An American couple named Patrick and Patricia Crowley noted that the rhythm method, which (although it isn't but for the sake of brevity) is timed abstinence to have sex on the most infertile times of the month, wasn't working. They ran an organization known as the Christian Family Movement and they surveyed their members, who shockingly agreed with them. There was a disconnect between the teaching and the teached. Mrs. Crowley even reported that a female member cried and despaired over being an occasion of sin for her husband. Therefore, based on this sociological data, she surmised that "the sacredness of conjugal love [must] not be violated by thermometers and calendars.” (Patty Crowley. “Patty Crowley Addresses The Papal Birth Control Commission (1965).” In American Catholic History: A Documentary Reader, edited by Mark Massa, S.J. and Catherine Osborne. 82.) The committee agreed with her, and they submitted a recommendation to adapt something along the lines of Resolution 15.

Well, Pope St. John XXIII died, there was a new conclave, and look! Paul VI. He got the results and said, "Thank you very much, but no." Pope Paul VI doubled down on Pope Pius XI's Casti connubii in his own encyclical Humanae Vitae. There's a lot in Humanae Vitae so I really recommend reading it on your own, but basically, think, in the most professional of terms, Casti connubii on steriods. If you're really interested, I can DM you my thesis's pages on Humanae Vitae but I really don't want to out this account to the entire Internet. Let me know. But the entirety of Humanae Vitae can be summed up as "“The Church, calling men back to the observance of the norms of the natural law...teaches that each and every marriage act must remain open to the transmission of life." (http://w2.vatican.va/content/paul-vi/en/encyclicals/documents/hf_p-vi_enc_25071968_humanae-vitae.html, Articles 11-12).

Unlike the 1930s, Catholics of the 1960s weren't going to take this silently, even from the Chair of Peter. There was a lot of dissent, most notably concerning Charles Curran of Georgetown who was censored by the Vatican for it but Georgetown stood by him in the name of academic freedom. There's a great chapter in this book about both Humanae Vitae and Charles Curran by the dean of Boston College Divinity School (https://www.amazon.com/American-Catholic-Revolution-Sixties-Changed/dp/0199734127).

1 case I will go into is the Winnipeg Statement, where the Canadian association of Catholic Bishops got together and basically said that the Canadian laity found it "either extremely difficult or even impossible to make their own all elements of this doctrine." (https://web.archive.org/web/20060829044505/http://www.catholic-legate.com/articles/winnipeg.html, Article 17). The assocation asked its priests to be sympathetic and kind when concerning this area, as there was a lot of confusion. The document was seen to be a Canadian acceptance of birth control, and the laity started to agree, as their bishops allowed it. And if anything, the dissent has shown that even bishops are confused about what Catholics should do about birth control, even when the Vatican and the Magisterium has been against it.

TL;DR: There was no specific figure against it in the past as it was the general norm but overall, the 1968 encyclical of Humanae Vitae built upon the 1930 encyclical of Casta connubi was the most influential action in the modern age concerning the Catholic view of the immorality of contraception.

N.B. Sorry for the edits; I pressed Enter too soon!