My hubby's Malaysian and I'm Singaporean. He went back to KL to work, then I joined him during pregnancy. I applied for 6 months social visit pass. The process is quite tedious, need to prepare documents and spend several hours queuing at the office. I then delivered baby in Malaysia.
If you're not working in Malaysia, I'm not sure if your wife can get the 6 months social visit pass. If she can't get it, would have to cross customs to renew, very tedious if living far away from JB.