There have been three known Jinchuriki for Kurama, all from the Uzumaki clan. Mito, Kushina and Naruto.
After Madara and Hashirama's final battle in the Valley of the End, Hashirama realized that Kurama was too dangerous to be walking alone in the world. Mito chose to seal Kyuubi within herself because of her knowledge of Uzumaki clan's Sealing Techniques, Exceptional Chakra and lifeforce, and the fact being close to First Hokage meant that he could control the situation if the seal weakened and Kyuubi went on rampage. Thus Mito was kind of convenient and obvious choice at that time.
Naruto on the otherhand was on the opposite end of spectrum. Minato was against the ropes and realized that the village needed Kyuubi's power to fight the threat posed by supposed Madara Uchiha. Naruto had the Uzumaki blood and sealing only half of Kurama allowed him more control as well.
Thus only Kushina's case was special, since it was deliberated and chosen specifically for being the Jinchuriki. The reasons of this are explained as follows.
- Kushina was chosen as the successor towards the twilight years of the clan. Uzumaki clan had almost disintegrated and a suitable successor would be very hard to find. Thus Kushina may have been the ONLY choice!
- Mito was a tested host for the Kyuubi and thus Leaf elders may have decided that the next Jinchuriki should be as close to Mito as possible. A special Kunoichi from Uzumaki clan with exceptional chakra? Thats what they were looking for.
- Kushina was eventually told why she had to leave her home of Uzushio and go to Konoha; because of her special chakra, she was to be the next jinchūriki of the Nine-Tailed Demon Fox. This can be the Uzumaki chakra or some other criteria, we don't know. (Source - Naruto chapter 500)
- Before the transfer was performed, Mito advised Kushina that love was the only way to tame the Nine-Tails and overcome its hate. Kyuubi was known as the incarnation of hate in the world and thus Mito may have felt that only a Kunoichi could control all the hate inside much more easily then any other ninja.