If Four Arms and the various other male Tetramands we see with exposed chests are any indicator, Tetramands have two sets of pectorals, like just about everything else we know about their biology. This likely means that they have two sets of breasts.
Obviously, this idea is then immediately countered by the fact that Tini, Looma, and the Matriarch from the reboot only display a single pair of knockers a piece, but I propose a different idea. Tetramands DO have two sets of breasts, but the second pair, located on their lower pectorals, are vestigial, little more than buds at the largest. They can swell to proper breasts with the hormonal rush caused by pregnancy, though they obviously remain dwarfed by the larger pair, even being capable of lactating, but outside of rare instances, they quickly recede back to their original size.
Likewise, it’s also fairly likely that Tetranands have two uteri, like kangaroos and wallabies, allowing Tetramand women to have multiple simultaneous pregnancies in various stages of development. Furthermore, given female Tetramands are biologically superior to the males in areas such as physical combat, they also almost certainly possess the ability to engage in embryonic diapause, the process in which a pregnancy can be “halted” in response to environmental pressures, like war time.
In conclusion, provided you can court her (beat her black and blue), you can have a Tetramand wife who’s constantly pregnant, lactating from four tits simultaneously meaning there’s never a shortage of milk, and still 100% combat effective all the while. Thank you for reading my autism.