No. Although second hand smoke is a health risk for everyone around it, I can't put it together with ld's. Ld's are primarily an issue where the thinking process for one area is wired a bit different. Instead of doing things in that area the way you do most stuff, you just don't get it or you take forever to figure it out. People learn how to work around it using their other skills.
Possibly. I honestly am not sure if this has been studied (or if so if it has been studied well). What is clear, however, is that all issues that develop from second hand smoke are bad. The person exposed to second hand smoke experiences the same risks (albeit lower overall) than the smoker him/herself.
During pregnancy. Exposure to second-hand smoke via mother can cause changes in the fetal brain, decreased cortical gray matter and atypical development of white matter. Clinical manifestations can be decreased iq, delays in speech & language, deficits in visual-spatial abilities, adhd & behavior problems. This is a big issue in las vegas for pregnant casino workers who are exposed for 8-hours per shift.
Maybe. Not sure data available to absolutely prove or disprove it, but common sense.
Too complex. How premature and why? Many children born early or exposed to substances in utero will have learning problems. Poor nutrition and exposure to toxins in infancy can also slow brain development. Lead exposure can be detrimental as can medications such as phenobarbital. Tobacco exposure is more likely to result in chronic asthma or other lung problems.