Can someone break down insurance for me?

I'm a FTM and have an struggling to understand the ins and outs of insurance, and what I'll be responsible for! 
I'm due in March. I have insurance through United HealthCare with my job. I have a $500 deductible, and my insurance covers 90% once that is met... My out of pocket maximum is $3,000. 
Can someone explain what happens if my deductible has not been met by the time I deliver? I pay my deductible by having it taken out of my check every 2 weeks, and when I did the math, by the end of March, my deductible will not have been met. Could I pay a little extra each month towards that? Like just call and say I want to pay towards my deductible? 
If my deductible has not been met, does insurance cover any of it? 
I'm just confused on everything! Thanks.