Brassica napus

There were 98 foods and non-alcoholic beverages listed on the FFQ. These were combined into 48 food groups on the basis of similarity of nutrient composition and comparable usage. For example, carrots, parsnips, swedes and turnips were combined in the ‘root vegetables’ group; bacon, ham, corned beef, meat pies and sausages were combined in the ‘processed meats’ group.
Principal component analysis is a statistical technique that produces new variables that are uncorrelated linear combinations of the dietary variables with maximum variance (20 (link)). PCA was performed on the reported frequencies of consumption of the 48 foods and food groups at the before, early and late pregnancy time points. The principal component analyses were based on the correlation matrix in order to adjust for unequal variances of the original variables. Natural dietary pattern scores were calculated by multiplying the coefficients for the 48 food groups at one time point by each individual’s standardized reported frequencies of consumption at the same time point. In order to calculate applied dietary pattern scores, frequencies of consumption in early and late pregnancy were standardized to the mean and standard deviation (SD) observed before pregnancy (since standardizing to the frequencies at the early or late pregnancy time point would remove information about increases or decreases in consumption between time points). Applied dietary pattern scores were then calculated by multiplying the coefficients from the PCA at the before-pregnancy time point by each individual’s standardized reported frequencies of consumption at the early and late pregnancy time points.
Natural PCA dietary scores are generated by definition with a mean of zero. The natural scores were divided by their standard deviation in order that the units of the scores were meaningful (standard deviation units). The applied scores were divided by the standard deviation of the before-pregnancy score, so that comparisons could be made in terms of change in standard deviation units.

The NCS-A interviews and parent SAQs assessed twelve CAs. These included three types of interpersonal loss (parental death, parental divorce, and other loss of contact with parents or caregivers), four types of parental maladjustment (mental illness, substance abuse, criminality, and family violence), four types of maltreatment (physical abuse, sexual abuse, emotional abuse, and neglect), and family economic adversity. Parental death and divorce were assessed only in regards to biological parents, not step-parents or other caregivers. The measure of other loss of contact with parents or caregivers, however, included any disruption of a relationship that lasted for six months or longer that either involved a caregiver leaving the respondent’s home (e.g., the biological mother abandoned the family) or the respondent leaving home (e.g., foster care placement or adoption). Respondents who were born to a single mother and never experienced any further disruption of this parenting arrangement were not coded as experiencing parental loss. We did not code separations from caregivers that involved the respondent being placed in a juvenile detention center or running away from home. We collected information on timing (i.e., the respondent’s age) for all parental loss events.
Physical and emotional abuse of the respondent by parents or caregivers were assessed with a modified version of the Conflict Tactics Scale (CTS).³² Sexual abuse was assessed with questions from the CIDI regarding sexual assault, attempted rape, and rape. Information was also collected on the age at which sexual abuse first occurred. Neglect was assessed with a battery of questions used in studies of child welfare that asked about frequency of not having adequate food, clothing, or medical care, having inadequate supervision, and being required to do chores that were age-inappropriate.³³ Parental criminality was assessed with questions in the CIDI and the SAQ about whether a parent either engaged in criminal activities like burglary or selling stolen property or was ever arrested or sent to prison for criminal activity.^{5 (link)} Parental mental illness (major depression, GAD, panic disorder, suicide attempt) and substance abuse were assessed with the Family History Research Diagnostic Criteria (FHRDC) Interview³⁴ and its extensions,^{35 (link)} as well as with items completed by parents in the SAQ. Family violence was assessed with the modified CTS and an item in the trauma section of the CIDI on the respondent’s age when they first observed inter-parental violence. Economic adversity was assessed with questions in the SAQ about whether the respondent’s family received welfare or other government assistance or often did not have enough money to pay for basic necessities of living.