Table 4.
Linear and longitudinal regression analyses for associations between Se biomarkers and growth outcomes
(95 % confidence intervals)
| Outcome | Se Biomarker* | Timepoint | n | Unadjusted β | 95 % CI | P | n | Adjusted β †,‡ | 95 % CI | P |
|---|---|---|---|---|---|---|---|---|---|---|
| Birth weight | WBSe delivery | Birth | 445 | –9·6 | –27·2, 7·9 | 0·3 | 416 | –26·6 | –44·3, −8·9 | 0·003 |
| WBSe venous cord | 441 | –23·6 | –37·4, −9·8 | 0·001 | 411 | –19·6 | –33·0, −6·1 | 0·005 | ||
| Serum Se delivery | 496 | –2·9 | –26·8, 21·1 | 0·8 | 486 | –16·4 | –38·8, 6·0 | 0·2 | ||
| SEPP1 delivery | 650 | 6·2 | –31·9, 44·3 | 0·7 | 643 | –37·5 | –73·0, −2·0 | 0·04 | ||
| SEPP1 venous cord | 555 | 43·3 | –10·9, 97·5 | 0·1 | 527 | 82·3 | 30·0, 134·7 | 0·002 | ||
| LAZ | WBSe delivery | Birth | 440 | –0·03 | –0·1, 0·03 | 0·3 | 412 | –0·05 | –0·1, 0·002 | 0·06 |
| 12 months | 552 | –0·006 | –0·05, 0·04 | 0·8 | 521 | –0·03 | –0·08, 0·01 | 0·2 | ||
| 24 months | 497 | 0·002 | –0·05, 0·05 | 0·9 | 468 | –0·02 | –0·07, 0·03 | 0·4 | ||
| LAZ§ | WBSe venous cord§ | Birth | 437 | –0·06 | –0·1, −0·01 | 0·009 | 407 | –0·05 | –0·1, −0·01 | 0·01 |
| 12 months | 466 | –0·05 | –0·09, −0·01 | 0·02 | 442 | –0·05 | –0·08, −0·01 | 0·02 | ||
| 24 months | 436 | –0·05 | –0·1, −0·01 | 0·01 | 409 | –0·04 | –0·08, 0·003 | 0·07 | ||
| LAZ | Serum Se delivery | Birth | 489 | 0·01 | –0·06, 0·08 | 0·8 | 479 | –0·03 | –0·1, 0·04 | 0·4 |
| 12 months | 605 | –0·01 | –0·07, 0·04 | 0·6 | 597 | –0·05 | –0·1, 0·01 | 0·09 | ||
| 24 months | 543 | –0·01 | –0·08, 0·05 | 0·7 | 533 | –0·05 | –0·1, 0·01 | 0·1 | ||
| LAZ | SEPP1 delivery | Birth | 643 | –0·01 | –0·1, 0·1 | 0·9 | 636 | –0·07 | –0·2, 0·04 | 0·2 |
| 12 months | 780 | 0·03 | –0·07, 0·1 | 0·6 | 775 | –0·01 | –0·1, 0·07 | 0·7 | ||
| 24 months | 716 | 0·03 | –0·07, 0·1 | 0·5 | 709 | –0·03 | –0·1, 0·06 | 0·5 | ||
| LAZ | SEPP1 venous cord | Birth | 551 | 0·1 | –0·02, 0·3 | 0·08 | 523 | 0·2 | 0·04, 0·4 | 0·01 |
| 12 months | 581 | 0·1 | –0·03, 0·3 | 0·1 | 555 | 0·07 | –0·09, 0·2 | 0·4 | ||
| 24 months | 542 | 0·2 | –0·006, 0·3 | 0·06 | 517 | 0·1 | –0·06, 0·3 | 0·2 | ||
| WAZ | WBSe delivery | Birth | 445 | –0·04 | –0·1, 0·001 | 0·06 | 416 | –0·07 | –0·1, −0·02 | 0·004 |
| 12 months | 551 | –0·01 | –0·06, 0·03 | 0·6 | 521 | –0·05 | –0·1, −0·005 | 0·03 | ||
| 24 months | 497 | 0·01 | –0·04, 0·07 | 0·7 | 468 | –0·02 | –0·08, 0·03 | 0·5 | ||
| WAZ | WBSe venous cord | Birth | 441 | –0·04 | –0·1, −0·003 | 0·03 | 411 | –0·05 | –0·08, −0·02 | 0·004 |
| 12 months | 466 | –0·04 | –0·08, 0·003 | 0·07 | 442 | –0·05 | –0·09, −0·004 | 0·03 | ||
| 24 months | 436 | –0·04 | –0·09, 0·007 | 0·1 | 409 | –0·03 | –0·08, 0·02 | 0·3 | ||
| WAZ | Serum Se delivery | Birth | 496 | –0·00002 | –0·06, 0·06 | 0·99 | 486 | –0·04 | –0·09, 0·02 | 0·2 |
| 12 months | 605 | –0·03 | –0·09, 0·04 | 0·4 | 597 | –0·07 | –0·1, 0·01 | 0·02 | ||
| 24 months | 542 | –0·008 | –0·08, 0·06 | 0·8 | 532 | –0·05 | –0·1, 0·02 | 0·2 | ||
| WAZ | SEPP1 delivery | Birth | 650 | –0·02 | –0·1, 0·1 | 0·6 | 643 | –0·09 | –0·2, 0·003 | 0·06 |
| 12 months | 779 | 0·004 | –0·09, 0·1 | 0·9 | 774 | –0·06 | –0·2, 0·04 | 0·2 | ||
| 24 months | 715 | 0·0003 | –0·1, 0·1 | 0·9 | 708 | –0·08 | –0·2, 0·03 | 0·1 | ||
| WAZ§ | SEPP1 venous cord§ | Birth | 555 | 0·1 | 0·006, 0·3 | 0·04 | 555 | 0·1 | 0·006, 0·3 | 0·04 |
| 12 months | 580 | 0·2 | 0·002, 0·3 | 0·05 | 554 | 0·08 | –0·09, 0·2 | 0·4 | ||
| 24 months | 541 | 0·2 | 0·04, 0·4 | 0·02 | 516 | 0·1 | –0·07, 0·3 | 0·2 | ||
| WFL | WBSe delivery | Birth | 395 | –0·02 | –0·1, 0·03 | 0·5 | 370 | –0·04 | –0·1, 0·02 | 0·2 |
| 12 months | 551 | –0·02 | –0·1, 0·03 | 0·5 | 521 | –0·05 | –0·1, −0·005 | 0·03 | ||
| 24 months | 497 | 0·01 | –0·04, 0·07 | 0·6 | 468 | –0·01 | –0·07, 0·04 | 0·6 | ||
| WFL | WBSe venous cord | Birth | 395 | –0·008 | –0·05, 0·03 | 0·7 | 369 | –0·03 | –0·07, 0·02 | 0·2 |
| 12 -months | 466 | –0·02 | –0·06, 0·02 | 0·3 | 442 | –0·03 | –0·07, 0·01 | 0·1 | ||
| 24 months | 436 | –0·01 | –0·06, 0·03 | 0·5 | 409 | –0·01 | –0·06, 0·04 | 0·7 | ||
| WFL | Serum Se delivery | Birth | 448 | 0·01 | –0·06, 0·08 | 0·7 | 439 | –0·02 | –0·09, 0·05 | 0·6 |
| 12 months | 605 | –0·03 | –0·08, 0·03 | 0·4 | 597 | –0·07 | –0·1, −0·007 | 0·03 | ||
| 24 months | 542 | –0·005 | –0·07, 0·06 | 0·9 | 532 | –0·03 | –0·1, 0·03 | 0·3 | ||
| WFL | SEPP1 delivery | Birth | 585 | –0·01 | –0·1, 0·1 | 0·8 | 579 | –0·06 | –0·2, 0·06 | 0·3 |
| 12 months | 779 | –0·02 | –0·1, 0·07 | 0·7 | 774 | –0·07 | –0·2, 0·02 | 0·1 | ||
| 24 months | 715 | –0·03 | –0·1, 0·07 | 0·6 | 708 | –0·09 | –0·2, 0·02 | 0·1 | ||
| WFL | SEPP1 venous cord | Birth | 500 | 0·1 | –0·1, 0·3 | 0·2 | 475 | 0·1 | –0·02, 0·3 | 0·09 |
| 12 months | 580 | 0·1 | –0·01, 0·3 | 0·07 | 554 | 0·06 | –0·1, 0·2 | 0·5 | ||
| 24 months | 541 | 0·2 | 0·005, 0·4 | 0·04 | 516 | 0·1 | –0·1, 0·3 | 0·3 | ||
| HCAZ | WBSe delivery | Birth | 444 | –0·02 | –0·07, 0·03 | 0·5 | 416 | –0·04 | –0·09, 0·01 | 0·1 |
| 12 months | 549 | –0·02 | –0·06, 0·03 | 0·4 | 518 | –0·02 | –0·07, 0·02 | 0·4 | ||
| 24 months | 494 | –0·005 | –0·05, 0·04 | 0·8 | 465 | –0·008 | –0·06, 0·04 | 0·7 | ||
| HCAZ | WBSe venous cord | Birth | 441 | 0·003 | –0·04, 0·04 | 0·9 | 411 | –0·002 | –0·04, 0·04 | 0·9 |
| 12 months | 461 | –0·02 | –0·06, 0·01 | 0·2 | 437 | –0·02 | –0·06, 0·02 | 0·3 | ||
| 24 months | 435 | –0·02 | –0·06, 0·01 | 0·2 | 408 | –0·02 | –0·05, 0·02 | 0·5 | ||
| HCAZ | Serum Se delivery | Birth | 494 | 0·02 | –0·05, 0·08 | 0·6 | 484 | –0·01 | –0·08, 0·05 | 0·7 |
| 12 months | 601 | 0·002 | –0·05, 0·06 | 0·9 | 593 | –0·005 | –0·1, −0·05 | 0·9 | ||
| 24 months | 539 | –0·02 | –0·07, 0·04 | 0·6 | 529 | –0·02 | –0·08, 0·04 | 0·4 | ||
| HCAZ | SEPP1 delivery | Birth | 646 | –0·1 | –0·2, 0·04 | 0·2 | 639 | –0·1 | –0·2, −0·02 | 0·02 |
| 12 months | 774 | 0·02 | –0·07, 0·1 | 0·7 | 769 | –0·01 | –0·1, 0·08 | 0·8 | ||
| 24 -months | 712 | –0·03 | –0·1, 0·06 | 0·6 | 705 | –0·06 | –0·2, 0·03 | 0·2 | ||
| HCAZ | SEPP1 venous cord | Birth | 554 | 0·04 | –0·1, 0·2 | 0·6 | 526 | 0·07 | –0·09, 0·2 | 0·4 |
| 12 months | 573 | –0·02 | –0·2, 0·1 | 0·8 | 547 | –0·06 | –0·2, 0·1 | 0·5 | ||
| 24 months | 539 | –0·03 | –0·2, 0·1 | 0·7 | 514 | –0·06 | –0·2, 0·1 | 0·5 |
WBSe, whole blood selenium; SEPP1, selenoprotein P; LAZ, length-for-age z-score; WAZ, weight-for-age z-score; WFL, weight-for-length; HCAZ, head circumference for age z-score; CRP, C-reactive protein.
WBSe scaled to represent the change in anthropometric outcome for every 10 µg/l increase in WBSe. Serum Se scaled to represent the change in anthropometric outcome for every 10 µg/l increase in serum Se. SEPP1 scaled to represent the change in anthropometric outcome for every 1000 µg/l increase in SEPP1.
Models adjusted for infant sex, gestational age at birth, season of birth, maternal age, maternal education, maternal height, maternal BMI, gravidity, vitamin D treatment group, delivery CRP, asset index quintiles, daily protein intake (kg), smoking and tobacco use during pregnancy.
No multi-collinearity problem was detected in models – assessment was conducted after generating directed acyclic graphs based on conceptual frameworks developed a priori.
Longitudinal analysis only conducted where unadjusted linear regression associations were significant for at least two of three age points.