Can multiple fields be grouped on one line of a form?

I am designing a form for a tablet. Typically forms are filled out vertically, but in landscape some fields could be represented on one line to save scrolling. For example: height and weight, or first and last name.

My questions are:

• Would too many groupings be confusing to users (e.g. gender and birthdate)?
• How should the multi-field design respond to both portrait and landscape layouts?