Here is short article jam-packed with non-Biblical advice.

This articles sets forth the worldview of modern family planning.
Family planning is normal.
The couple may not be married.
Premarital relations are normal, and even so while in an “unstable” relationship.
Bickering and fighting in relationships is normal, but requires professional help.
Babies bring more stress into relationships.
Personal goals are more important than babies, even a frivolous trip.
Educational goals are more important than babies.
Career goals are more important than babies.
It is normal for mothers to work, while leaving there babies to the care of others.
It is fine to put off having a baby while you are young.
It is acknowledged that if you want a baby, you can’t put it off as fertility declines with age.
Babies stress finances, so it is risky to have a baby.
Finances are more important than babies.
Additional babies take away from time with spouse and the other children; babies may damage other relationships.
One should write out the pros and cons of having additional babies.
Spacing out children is a good idea; having them too close together is a bad idea.
It’s unhealthy to have babies too close together.
The personality of children already in the home are an important factor in determining if/when to have the next child.
A couple tries to have, or tries to not have, a baby.

Two statements worth noting:

Having a baby stresses a relationship – it never fixes one.
While there’s never a “perfect” time to have a baby, you should wait for a “good” time.

“Having a baby stresses a relationship – it never fixes one.”