The First Commandment that God gave to Adam & Eve Pertained to their Potential for Parenthood as Husband and Wife. We Declare that God’s Commandment for His Children to Multiply and Replenish the Earth remains in Force.

More and more young people view marriage ‘as a couples relationship, designed to fulfill the emotional needs of adults, rather than an institution for bringing up children.’ …Another disturbing challenge to the family, is that children are becoming less valued. In many parts of the world, people are having fewer children. Abortion is probably the clearest sign that couples do not want children. An estimated one-quarter of all pregnancies worldwide end by induced abortion. 
-James E. Faust, Challenges Facing the Family, Jan. 10, 2004

Adam and Eve ventured forth to multiply and replenish the earth as they had been commanded to do. The creation of their bodies in the image of God, as a separate creation, was crucial to the plan. Their subsequent Fall was essential if the condition of mortality was to exist and the plan to proceed. 
-Boyd K. Packer, Who is Jesus Christ?, March 2008


 
Children - Neil L. Anderson - October 2011 General Conference

 
A "Mother Heart" - Julie B. Beck - April 2004 General Conference

Scriptures:

So God created man in his own image, in the image of God created he him; male and female created he them. And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.
-Genesis 1:27-28, Holy Bible

But if one or either of the ten virgins, after she is espoused, shall be with another man, she has committed adultery, and shall be destroyed; for they are given unto him to multiply and replenish the earth, according to my commandment, and to fulfill the promise which was given by my Father before the foundation of the world, and for their exaltation in the eternal worlds, that they may bear the souls of men; for herein is the work of my Father continued, that he may be glorified.
-Doctrine & Covenants 132:63

Definitions:

Commandment - a command or mandate
Potential - capable of being or becoming
Parenthood - a person acting as a father or mother; guardian
-Dictionary.com