Please help with following question:

Background

Every year, more than 1 million young children in the United States and 200,000 young children in the UK experience a fall that requires urgent care. Between 2010 and 2012, British researchers conducted a study on risk factors for early childhood falls from furniture in six regions in England.

Study Description

Investigators recruited children (aged 0 to 4 years) who had presented to a hospital or urgent care center due to a fall from indoor or outdoor furniture in their own, private homes. Falls from play equipment (i.e., trampolines, play structures, swings, or slides) were excluded from the study. Parents of children who had fallen were approached via telephone and mail within 72 hours of the injury. For every child that experienced a fall from furniture at his/her home, up to four other children who had not fallen from furniture at their homes were recruited. Investigators selected children who were of the same sex, age (within 4 months), calendar time (within 4 months), and region as those children who had fallen from furniture. These other children were recruited by mail from the general practice clinics in the same region as each of the fall from furniture accidents. All parents completed questionnaires about the use of various safety behaviors, safety equipment, and home hazards within the previous week.

The investigators matched those with and without falls from furniture by age. Given this, will the data in this study accurately reflect the true association between age and the likelihood of falls from furniture? If so, why? If not, why not, and how will the observed association differ from the true association?

Norwich	146 (21.7%)	644 (24.3%)
Newcastle	65 (9.7%)	206 (7.8%)
Age (months)
0-12	223 (33.2%)	741 (28.0%)
13-36	296 (44.1%)	1270 (48.0%)
37-62	153 (54.3%)	637 (24.1%)
Maternal age <19 at birth	285 (45.4%)	1093 (44.9%)
Parental assessment of child's ability to climb
Unlikely	166 (25.4%)	536 (20.7%)
Somewhat likely	85 (13.0%)	235 (9.1%)
Very likely	403 (61.6%)	1820 (70.2%)
Hours of out-of-home child care, median (IQR)	7.5 (18.0)	12.0 (21.0)