Table 4.

Change in Patient Characteristics Over Time

		1990–1999		2000–2009		2010–2019
All Patients
Number of Total Patients	2626		2929		1881
Multiple Gestation (n, %)	401	15%	470	16%	451	24%	p < 0.001ǂ
Birthweight (grams, mean)	1076.3		1091.0		1150.4		p < 0.001*
Proportion (n, %)
< 750g	527	21%	730	26%	435	23%
750–999g	555	22%	551	19%	333	18%
1000–1249g	619	25%	514	18%	316	17%
1250–1500g	469	19%	567	20%	375	20%
>1500g	317	13%	485	17%	404	22%
GA (weeks, mean)	28.3		28.3		28.6		p < 0.001*
Proportion (n, %)
<27w	756	30%	912	32%	563	30%
27–32w	1317	53%	1401	49%	958	51%
>32w	415	17%	522	18%	354	19%
ROP Patients
Number of Patients (% total)	831	32%	894	31%	473	25%	p < 0.001ǂ
Multiple Gestation (n, %)	123	15%	139	16%	92	19%	p = 0.075ǂ
Birthweight (grams, mean)	858.0		815.1		780.7		p < 0.001*
Proportion (n, %)
< 750g	267	35%	411	47%	257	55%
750–999g	304	40%	283	33%	138	29%
1000–1249g	143	19%	123	14%	48	10%
1250–1500g	38	5.0%	40	4.6%	23	4.9%
>1500g	6	0.8%	12	1.4%	5	1.1%
GA (weeks, mean)	26.7		26.3		25.8		p < 0.001*
Proportion (n, %)
<27w	408	54%	529	61%	338	72%
27–32w	310	41%	325	37%	128	27%
>32w	39	5.2%	16	1.8%	5	1.1%
Non-ROP Patients
Number of Patients (% total)	1795	68%	2035	69%	1408	75%
Multiple Gestation (n, %)	278	15%	331	16%	359	25%	p < 0.001ǂ
Birthweight (grams, mean)	1275.5		1212.2		1172.0
Proportion (n, %)
< 750g	260	15%	319	16%	178	13%
750–999g	251	15%	268	14%	195	14%
1000–1249g	476	28%	391	20%	268	19%
1250–1500g	431	25%	527	27%	352	25%
>1500g	311	18%	473	24%	399	29%
GA (weeks, mean)	29.6		29.2		29.0
Proportion (n, %)
<27w	348	20%	383	19%	225	16%
27–32w	1007	58%	1076	55%	830	59%
>32w	376	22%	506	26%	349	25%

^ǂChi-square analysis comparing change across decades

^*ANOVA comparing change across time

Abbreviations: BW - birthweight, g - grams, GA - gestational age, n - number, std dev - standard deviation, w - weeks