There are some factors that cause a delay in getting a margin call. But you still need to manage your unprofitable trades before any more losses. 

• Make sure you have enough funds in your account to keep your trades open and don't open more positions than you can manage with your account equity. Pay attention that what leverage you are using in your account. If you choose a lower leverage, make sure you have sufficient funds to open and maintain trades. If you choose a higher leverage, make sure you don't open more trades than you can handle with your account equity.

• Manage your risk. Control how many lots are traded at one time. Keep an eye on your usable and used margin.
  

• Place stops to protect your equity from significant losses.

If you are approching the margin call point, add more funds to your account and close the unprofitable trades before the system (MT4) does it for you.