The Pregnancy of a Woman is evidence of her adultery, but men are free in absence of the 4 male eyewitnesses

https://www.islamweb.net/en/fatwa/28539/does-an-unmarried-womans-pregnancy-entail-the-application-of-hadd-of-zina

The famous opinion of the Maaliki scholars suggests that the pregnancy of an unmarried woman is evidence of Zina, and they do not accept her claim of rape except if there is proof. This is supported by the fact that ‘Umar ibn Al-Khattaab  was reported to have said:

Sahih Muslim 1691a:

However, the majority of scholars say that casting"doubts" about pregnancy are enough to save oneself from punishment.

The majority of jurists relied on the narration which relates that:

أن عمر رضي الله عنه أتي بامرأة ليس لها زوج قد حملت! فسألها عمر؟ فقالت: إني امرأة ثقيلة الرأس وقع علي رجل وأنا نائمة، فما استيقظت حتى فرغ، فدرأ عنها الحد.

A pregnant, unmarried woman was brought to ‘Umar ibn Al-Khattab  who asked her about that and she replied, "I am heavy-headed, and a man came and had sexual intercourse with me while I was deeply asleep. I did not wake up except after the man had finished (having intercourse with me)." ‘Umar ibn Al-Khattaab  dismissed the (application of) Hadd in this incident. [Ibn Abi Shaybah, Sa‘eed ibn Mansoor, and Al-Bayhaqi]

Ibn Taymiyyah  said, doubts are only for a woman who is not a "slave" and does not have a husband:

"If a woman who has neither a husband nor a master (meaning that she is not a slave girl) got pregnant, the Hadd for Zina should be implemented unless she claims that this took place due to a Shubhah (having intercourse mistakenly believing it is lawful while in fact it is unlawful." [Al-Fataawa Al-Kubra]

Muhammad punished his slave girl for being pregnant:

Sunan Abu Dawud, 4473:

Narrated Ali ibn AbuTalib: A slave-girl belonging to the house of the Messenger of Allah (ﷺ) committed fornication. He (the Prophet) said: Rush up, Ali, and inflict the prescribed punishment on her. I then hurried up, and saw that blood was flowing from her, and did not stop. So I came to him and he said: Have you finished inflicting (punishment on her)? I said: I went to her while her blood was flowing. He said: Leave her alone till her bleeding stops; then inflict the prescribed punishment on her. And inflict the prescribed punishment on those whom your right hands possess (i.e. slaves).
Abu Dawud said: A similar tradition has been transmitted by Abu al-Ahwas from 'Abd al-A'la, and also by Shu'bah from 'Abd al-A'la. This version has: He said: Do not give her beating until she gives birth to a child. But the former (version) is sounder.

It seems that the man was not punished, but only the slave girl was punished in this case, while she was charged for adultery due to pregnancy. 

This shows that a free Muslim rapist will face no chagres, as he neither becomes pregnant, nor 4 male eyewitnesses are possible who see the action of sex as khol stick goes into kohl container.

Muwatta Malik Book 41, Hadith 15:

Malik said, "The position with us about a woman who is found to be pregnant and has no husband and she says, 'I was forced,' or she says, 'I was married,' is that it is not accepted from her and the hadd is inflicted on her unless she has a clear proof of what she claims about the marriage or that she was forced or she comes bleeding if she was a virgin or she calls out for help so that someone comes to her and she is in that state or what resembles it of the situation in which the violation occurred." He said, "If she does not produce any of those, the hadd is inflicted on her and what she claims of that is not accepted from her."

And the largest Fatwa Website (run by Saudi Salafi Muftis) Islam Q&A writes in its fatwa (link):

Rape is essentially zina (fornication or adultery) and is proven in the same way as zina is proven, which is with four witnesses. The punishment is one hundred lashes if the man was a virgin and stoning if he was previously married ...  Ibn ‘Abd al-Barr (may Allah have mercy on him) said: She is not to be punished if it is proven that he forced her and overpowered her. That may be known from her having screamed and shouted for help. (Al-Istidhkaar, 7/146 ) ...  

It is very difficult for a raped woman (or a small child girl) to bring proof of her rape. There are no people present where she is raped who can hear her calls for help, and blood also does not always come. The biggest problem is, perhaps 100% of women don't even know about these Islamic Rulings about rape that they have to immediately present their blood in public. Their first reaction is to hide their face along with their rape. Their own families could kill them in the name of Ghairah. 

Do you think that small child girls could act upon these Islamic rulings if they are being raped by their own fathers, brothers, uncles or the Mullah in the Quran schools? 

The Largest Islamic Website is Islamweb.Net. It records this Fatwa (link):

“This means that if a woman accused a pious man of forcing her into adultery and there were no witnesses to prove her claim and she did not drag him by his clothes (to prove the offense), then she should be subjected to the hadd of slander whether or not she is well-known for chastity she should be subjected to the hadd of zina if she becomes pregnant as a result. The same ruling applies if she is proven non-pregnant unless she retracts her claim. If she drags him by his clothes and reports the crime of her own volition, then the hadd of zina is waived from her even if she is proven pregnant given the public defamation that she brought upon herself by reporting the offense. She is still subject to the hadd of slander and has no right to ask the man whom she accused to take an oath and swear to his innocence of the charge brought against him. On the other hand, if she accused a dissolute man of such a crime and she did not drag him by his clothes, then she is not subject to the hadd of slander or zina unless she is proven pregnant. However, if she dragged him by his clothes, then the hadd of zina is waived from her even if she is proven pregnant and the hadd of slander is waived from her as well. Lastly, if she accused a man whose religiosity is unknown and she did not drag him by his clothes, then she is subject to both the hadd of slander and that of zina. If she dragged him by his clothes, then she is not subject for that to the hadd of slander...”

Please tell us, how a poor woman/girl, who has been raped, has a force to drag her rapist in front of people?

And without eye-witnesses, and without have the power/chance to drag her rapist with his clothes in public, if she becomes pregnant, then she will be punished for 80 lashes (if she is a virgin), or she will get stoned if she is a married woman. And her child will automatically become a Bastard (Islamic Term: Walad-ul-haram ولدألحرأم). Do you see any Divine Justice with such a poor woman/girl here?

Here are some examples of these flawed Islamic Rulings:

• Bariya Ibrahim Magazu is a Nigerian teenager who was lashed 100 times after she became pregnant before marriage. She claimed she had been raped by several men who had loaned money to her father. However, the state she lived in, Zamfara, had transitioned to Sharia law, and the male judges presiding over her case acquitted the accused men, but upheld her hadd sentence.

• Safiya Hussaini is another Nigerian woman who was sentenced to stoning after becoming pregnant following her divorce. Her state, Sokoto, had also recently transitioned to Sharia law. She claimed that she had been raped repeatedly by her neighbor, but the court acquitted her neighbor while sentencing her to death. Fortunately, she was acquitted by a higher court, because her alleged adultery must have happened before Sharia was actually implemented in Sokoto.