If, as per Islamic laws, a Muslim man can have four wives, then how does the female and male ratio get maintained in Islamic countries?

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RiXingStar

Lives in Srinagar, Jammu and Kashmir

Even though most muslims are aware that they can have multiple wives but still a very tiny fraction have multiple wives like 1% or 2% , mostly in Arab countries. So that doesn't pose any significant disbalance to female to male ratio.

Most modern Muslims view the practice of polygyny as allowed, but unusual and not recommended.[16]

 The practice of polygyny is often viewed in its historical context, as the marriage was the only way for a woman to be provided for during the time of Muhammad.[17]

 Many countries today either outlaw the practice of polygyny or place restrictions on it.

Several countries, such as Libya

, allow polygyny with few or no restrictions.[18]

In Indonesia

, a majority-Muslim secular nation, polygyny is rare. In 2018, it was practiced by approximately 1% of the population.[19]

Polygamy has always been rare among South Asian Muslims.[20]

 In medieval India and Punjab, most ordinary Muslim men only had one wife. Polygamy was rare outside the wealthy class, unless in case of infertility of the first wife.[21]

 It was rare for a lower or middle class woman to have a rival.[22]

Most men in the Ottoman Empire were monogamous while only a small minority were polygamous. Salomon Schweigger

 who travelled in the Ottoman Empire wrote in the late 16th century that polygamy was absent. In the 1700s wealthy families in Istanbul looked down on elite men who married more than once. High level officials were required to leave their wives and concubines if they were to marry an Ottoman princess. Lady Mary Wortley Montau visited the Ottoman Empire in 1717 and noticed that while Muslims were allowed four wives no "man of quality" used this right. Of all the top Ottoman men at court, the author only found one who had female slaves.[23]

Some muslim countries even have fully banned the practice of Polygyny(multiple wives) like Turkey and Tunisia while others have places restrictions on the same like

• Sudan
   (1929)[28]
• India
   (1939)[28]
• Algeria
  [25]
• Jordan
   (1951)[28]
• Syria
   (1953)[28]
• Morocco
   (1958)[28]
• Bangladesh
  [25]
• Iraq
   (1959)[28]
• Iran
   (1967, 1975)[28]
• Kuwait
  [25]
• Lebanon
  [25]

Some countries, including India, Iran, Iraq, Bangladesh, Algeria, Lebanon, Morocco, Jordan, and Kuwait, allow women to include a clause prohibiting polygyny in marriage contracts.[25]

[26]

 Other countries, such as Iran and Pakistan, require that a man get permission to take a second wife from his first wife, and then show the court proof of his first wife's consent.[25]

 Finally, countries such as Malaysia state that a man must get permission from both his wife and from the governmental religious authority in order to take a second.